The Entire Curl Manual

This manual was appended to text directly from bash but for your ease of use I’ve simply copied it here.

NAME
curl – transfer a URL

SYNOPSIS
curl [options] [URL…]

DESCRIPTION
curl is a tool to transfer data from or to a server, using one of the
supported protocols (DICT, FILE, FTP, FTPS, GOPHER, HTTP, HTTPS, IMAP,
IMAPS, LDAP, LDAPS, POP3, POP3S, RTMP, RTSP, SCP, SFTP, SMTP, SMTPS,
TELNET and TFTP). The command is designed to work without user inter-
action.

curl offers a busload of useful tricks like proxy support, user authen-
tication, FTP upload, HTTP post, SSL connections, cookies, file trans-
fer resume, Metalink, and more. As you will see below, the number of
features will make your head spin!

curl is powered by libcurl for all transfer-related features. See
libcurl(3) for details.

URL
The URL syntax is protocol-dependent. You’ll find a detailed descrip-
tion in RFC 3986.

You can specify multiple URLs or parts of URLs by writing part sets
within braces as in:

http://site.{one,two,three}.com

or you can get sequences of alphanumeric series by using [] as in:

ftp://ftp.numericals.com/file[1-100].txt
ftp://ftp.numericals.com/file[001-100].txt (with leading zeros)
ftp://ftp.letters.com/file[a-z].txt

Nested sequences are not supported, but you can use several ones next
to each other:

http://any.org/archive[1996-1999]/vol[1-4]/part{a,b,c}.html

You can specify any amount of URLs on the command line. They will be
fetched in a sequential manner in the specified order.

You can specify a step counter for the ranges to get every Nth number
or letter:

http://www.numericals.com/file[1-100:10].txt
http://www.letters.com/file[a-z:2].txt

If you specify URL without protocol:// prefix, curl will attempt to
guess what protocol you might want. It will then default to HTTP but
try other protocols based on often-used host name prefixes. For exam-
ple, for host names starting with “ftp.” curl will assume you want to
speak FTP.

curl will do its best to use what you pass to it as a URL. It is not
trying to validate it as a syntactically correct URL by any means but
is instead very liberal with what it accepts.

curl will attempt to re-use connections for multiple file transfers, so
that getting many files from the same server will not do multiple con-
nects / handshakes. This improves speed. Of course this is only done on
files specified on a single command line and cannot be used between
separate curl invokes.

PROGRESS METER
curl normally displays a progress meter during operations, indicating
the amount of transferred data, transfer speeds and estimated time
left, etc.

curl displays this data to the terminal by default, so if you invoke
curl to do an operation and it is about to write data to the terminal,
it disables the progress meter as otherwise it would mess up the output
mixing progress meter and response data.

If you want a progress meter for HTTP POST or PUT requests, you need to
redirect the response output to a file, using shell redirect (>), -o
[file] or similar.

It is not the same case for FTP upload as that operation does not spit
out any response data to the terminal.

If you prefer a progress “bar” instead of the regular meter, -# is your
friend.
OPTIONS
Options start with one or two dashes. Many of the options require an
addition value next to it.

The short “single-dash” form of the options, -d for example, may be
used with or without a space between it and its value, although a space
is a recommended separator. The long “double-dash” form, –data for
example, requires a space between it and its value.

Short version options that don’t need any additional values can be used
immediately next to each other, like for example you can specify all
the options -O, -L and -v at once as -OLv.

In general, all boolean options are enabled with –option and yet again
disabled with –no-option. That is, you use the exact same option name
but prefix it with “no-“. However, in this list we mostly only list and
show the –option version of them. (This concept with –no options was
added in 7.19.0. Previously most options were toggled on/off on
repeated use of the same command line option.)

-#, –progress-bar
Make curl display progress as a simple progress bar instead of
the standard, more informational, meter.

-0, –http1.0
(HTTP) Tells curl to use HTTP version 1.0 instead of using its
internally preferred: HTTP 1.1.

–http1.1
(HTTP) Tells curl to use HTTP version 1.1. This is the internal
default version. (Added in 7.33.0)

–http2.0
(HTTP) Tells curl to issue its requests using HTTP 2.0. This
requires that the underlying libcurl was built to support it.
(Added in 7.33.0)

-1, –tlsv1
(SSL) Forces curl to use TLS version 1 when negotiating with a
remote TLS server.

-2, –sslv2
(SSL) Forces curl to use SSL version 2 when negotiating with a
remote SSL server.

-3, –sslv3
(SSL) Forces curl to use SSL version 3 when negotiating with a
remote SSL server.

-4, –ipv4
If curl is capable of resolving an address to multiple IP ver-
sions (which it is if it is IPv6-capable), this option tells
curl to resolve names to IPv4 addresses only.

-6, –ipv6
If curl is capable of resolving an address to multiple IP ver-
sions (which it is if it is IPv6-capable), this option tells
curl to resolve names to IPv6 addresses only.

-a, –append
(FTP/SFTP) When used in an upload, this will tell curl to append
to the target file instead of overwriting it. If the file
doesn’t exist, it will be created. Note that this flag is
ignored by some SSH servers (including OpenSSH).

-A, –user-agent <agent string>
(HTTP) Specify the User-Agent string to send to the HTTP server.
Some badly done CGIs fail if this field isn’t set to
“Mozilla/4.0”. To encode blanks in the string, surround the
string with single quote marks. This can also be set with the
-H, –header option of course.

If this option is used several times, the last one will be used.

–anyauth
(HTTP) Tells curl to figure out authentication method by itself,
and use the most secure one the remote site claims to support.
This is done by first doing a request and checking the response-
headers, thus possibly inducing an extra network round-trip.
This is used instead of setting a specific authentication
method, which you can do with –basic, –digest, –ntlm, and
–negotiate.

Note that using –anyauth is not recommended if you do uploads
from stdin, since it may require data to be sent twice and then
the client must be able to rewind. If the need should arise when
uploading from stdin, the upload operation will fail.

-b, –cookie <name=data>
(HTTP) Pass the data to the HTTP server as a cookie. It is sup-
posedly the data previously received from the server in a “Set-
Cookie:” line. The data should be in the format “NAME1=VALUE1;
NAME2=VALUE2”.

If no ‘=’ symbol is used in the line, it is treated as a file-
name to use to read previously stored cookie lines from, which
should be used in this session if they match. Using this method
also activates the “cookie parser” which will make curl record
incoming cookies too, which may be handy if you’re using this in
combination with the -L, –location option. The file format of
the file to read cookies from should be plain HTTP headers or
the Netscape/Mozilla cookie file format.

NOTE that the file specified with -b, –cookie is only used as
input. No cookies will be stored in the file. To store cookies,
use the -c, –cookie-jar option or you could even save the HTTP
headers to a file using -D, –dump-header!

If this option is used several times, the last one will be used.

-B, –use-ascii
(FTP/LDAP) Enable ASCII transfer. For FTP, this can also be
enforced by using an URL that ends with “;type=A”. This option
causes data sent to stdout to be in text mode for win32 systems.

–basic
(HTTP) Tells curl to use HTTP Basic authentication. This is the
default and this option is usually pointless, unless you use it
to override a previously set option that sets a different
authentication method (such as –ntlm, –digest, or –negoti-
ate).

-c, –cookie-jar <file name>
(HTTP) Specify to which file you want curl to write all cookies
after a completed operation. Curl writes all cookies previously
read from a specified file as well as all cookies received from
remote server(s). If no cookies are known, no file will be writ-
ten. The file will be written using the Netscape cookie file
format. If you set the file name to a single dash, “-“, the
cookies will be written to stdout.

This command line option will activate the cookie engine that
makes curl record and use cookies. Another way to activate it is
to use the -b, –cookie option.

If the cookie jar can’t be created or written to, the whole curl
operation won’t fail or even report an error clearly. Using -v
will get a warning displayed, but that is the only visible feed-
back you get about this possibly lethal situation.

If this option is used several times, the last specified file
name will be used.

-C, –continue-at <offset>
Continue/Resume a previous file transfer at the given offset.
The given offset is the exact number of bytes that will be
skipped, counting from the beginning of the source file before
it is transferred to the destination. If used with uploads, the
FTP server command SIZE will not be used by curl.

Use “-C -” to tell curl to automatically find out where/how to
resume the transfer. It then uses the given output/input files
to figure that out.

If this option is used several times, the last one will be used.

–ciphers <list of ciphers>
(SSL) Specifies which ciphers to use in the connection. The list
of ciphers must specify valid ciphers. Read up on SSL cipher
list details on this URL:
http://www.openssl.org/docs/apps/ciphers.html

NSS ciphers are done differently than OpenSSL and GnuTLS. The
full list of NSS ciphers is in the NSSCipherSuite entry at this
URL: http://git.fedora-
hosted.org/cgit/mod_nss.git/plain/docs/mod_nss.html#Directives

If this option is used several times, the last one will be used.

–compressed
(HTTP) Request a compressed response using one of the algorithms
curl supports, and save the uncompressed document. If this
option is used and the server sends an unsupported encoding,
curl will report an error.

–connect-timeout <seconds>
Maximum time in seconds that you allow the connection to the
server to take. This only limits the connection phase, once
curl has connected this option is of no more use. Since 7.32.0,
this option accepts decimal values, but the actual timeout will
decrease in accuracy as the specified timeout increases in deci-
mal precision. See also the -m, –max-time option.

If this option is used several times, the last one will be used.

–create-dirs
When used in conjunction with the -o option, curl will create
the necessary local directory hierarchy as needed. This option
creates the dirs mentioned with the -o option, nothing else. If
the -o file name uses no dir or if the dirs it mentions already
exist, no dir will be created.

To create remote directories when using FTP or SFTP, try –ftp-
create-dirs.

–crlf (FTP) Convert LF to CRLF in upload. Useful for MVS (OS/390).

–crlfile <file>
(HTTPS/FTPS) Provide a file using PEM format with a Certificate
Revocation List that may specify peer certificates that are to
be considered revoked.

If this option is used several times, the last one will be used.

(Added in 7.19.7)
-d, –data <data>
(HTTP) Sends the specified data in a POST request to the HTTP
server, in the same way that a browser does when a user has
filled in an HTML form and presses the submit button. This will
cause curl to pass the data to the server using the content-type
application/x-www-form-urlencoded. Compare to -F, –form.

-d, –data is the same as –data-ascii. To post data purely
binary, you should instead use the –data-binary option. To URL-
encode the value of a form field you may use –data-urlencode.

If any of these options is used more than once on the same com-
mand line, the data pieces specified will be merged together
with a separating &-symbol. Thus, using ‘-d name=daniel -d
skill=lousy’ would generate a post chunk that looks like
‘name=daniel&skill=lousy’.

If you start the data with the letter @, the rest should be a
file name to read the data from, or – if you want curl to read
the data from stdin. Multiple files can also be specified. Post-
ing data from a file named ‘foobar’ would thus be done with
–data @foobar. When –data is told to read from a file like
that, carriage returns and newlines will be stripped out.

-D, –dump-header <file>
Write the protocol headers to the specified file.

This option is handy to use when you want to store the headers
that an HTTP site sends to you. Cookies from the headers could
then be read in a second curl invocation by using the -b,
–cookie option! The -c, –cookie-jar option is however a better
way to store cookies.

When used in FTP, the FTP server response lines are considered
being “headers” and thus are saved there.

If this option is used several times, the last one will be used.

–data-ascii <data>
See -d, –data.

–data-binary <data>
(HTTP) This posts data exactly as specified with no extra pro-
cessing whatsoever.

If you start the data with the letter @, the rest should be a
filename. Data is posted in a similar manner as –data-ascii
does, except that newlines and carriage returns are preserved
and conversions are never done.

If this option is used several times, the ones following the
first will append data as described in -d, –data.

–data-urlencode <data>
(HTTP) This posts data, similar to the other –data options with
the exception that this performs URL-encoding. (Added in 7.18.0)
To be CGI-compliant, the <data> part should begin with a name
followed by a separator and a content specification. The <data>
part can be passed to curl using one of the following syntaxes:

content
This will make curl URL-encode the content and pass that
on. Just be careful so that the content doesn’t contain
any = or @ symbols, as that will then make the syntax
match one of the other cases below!

=content
This will make curl URL-encode the content and pass that
on. The preceding = symbol is not included in the data.

name=content
This will make curl URL-encode the content part and pass
that on. Note that the name part is expected to be URL-
encoded already.

@filename
This will make curl load data from the given file
(including any newlines), URL-encode that data and pass
it on in the POST.

name@filename
This will make curl load data from the given file
(including any newlines), URL-encode that data and pass
it on in the POST. The name part gets an equal sign
appended, resulting in name=urlencoded-file-content. Note
that the name is expected to be URL-encoded already.

–delegation LEVEL
Set LEVEL to tell the server what it is allowed to delegate when
it comes to user credentials. Used with GSS/kerberos.

none Don’t allow any delegation.

policy Delegates if and only if the OK-AS-DELEGATE flag is set
in the Kerberos service ticket, which is a matter of
realm policy.

always Unconditionally allow the server to delegate.

–digest
(HTTP) Enables HTTP Digest authentication. This is an authenti-
cation scheme that prevents the password from being sent over
the wire in clear text. Use this in combination with the normal
-u, –user option to set user name and password. See also
–ntlm, –negotiate and –anyauth for related options.

If this option is used several times, only the first one is
used.

–disable-eprt
(FTP) Tell curl to disable the use of the EPRT and LPRT commands
when doing active FTP transfers. Curl will normally always first
attempt to use EPRT, then LPRT before using PORT, but with this
option, it will use PORT right away. EPRT and LPRT are exten-
sions to the original FTP protocol, and may not work on all
servers, but they enable more functionality in a better way than
the traditional PORT command.

–eprt can be used to explicitly enable EPRT again and –no-eprt
is an alias for –disable-eprt.

Disabling EPRT only changes the active behavior. If you want to
switch to passive mode you need to not use -P, –ftp-port or
force it with –ftp-pasv.

–disable-epsv
(FTP) Tell curl to disable the use of the EPSV command when
doing passive FTP transfers. Curl will normally always first
attempt to use EPSV before PASV, but with this option, it will
not try using EPSV.

–epsv can be used to explicitly enable EPSV again and –no-epsv
is an alias for –disable-epsv.

Disabling EPSV only changes the passive behavior. If you want to
switch to active mode you need to use -P, –ftp-port.

–dns-interface <interface>
Tell curl to send outgoing DNS requests through <interface>.
This option is a counterpart to –interface (which does not
affect DNS). The supplied string must be an interface name (not
an address).

This option requires that libcurl was built with a resolver
backend that supports this operation. The c-ares backend is the
only such one. (Added in 7.33.0)

–dns-ipv4-addr <ip-address>
Tell curl to bind to <ip-address> when making IPv4 DNS requests,
so that the DNS requests originate from this address. The argu-
ment should be a single IPv4 address.

This option requires that libcurl was built with a resolver
backend that supports this operation. The c-ares backend is the
only such one. (Added in 7.33.0)

–dns-ipv6-addr <ip-address>
Tell curl to bind to <ip-address> when making IPv6 DNS requests,
so that the DNS requests originate from this address. The argu-
ment should be a single IPv6 address.

This option requires that libcurl was built with a resolver
backend that supports this operation. The c-ares backend is the
only such one. (Added in 7.33.0)

–dns-servers <ip-address,ip-address>
Set the list of DNS servers to be used instead of the system
default. The list of IP addresses should be separated with com-
mas. Port numbers may also optionally be given as :<port-number>
after each IP address.

This option requires that libcurl was built with a resolver
backend that supports this operation. The c-ares backend is the
only such one. (Added in 7.33.0)

-e, –referer <URL>
(HTTP) Sends the “Referer Page” information to the HTTP server.
This can also be set with the -H, –header flag of course. When
used with -L, –location you can append “;auto” to the –referer
URL to make curl automatically set the previous URL when it fol-
lows a Location: header. The “;auto” string can be used alone,
even if you don’t set an initial –referer.

If this option is used several times, the last one will be used.

-E, –cert <certificate[:password]>
(SSL) Tells curl to use the specified client certificate file
when getting a file with HTTPS, FTPS or another SSL-based proto-
col. The certificate must be in PKCS#12 format if using Secure
Transport, or PEM format if using any other engine. If the
optional password isn’t specified, it will be queried for on the
terminal. Note that this option assumes a “certificate” file
that is the private key and the private certificate concate-
nated! See –cert and –key to specify them independently.

If curl is built against the NSS SSL library then this option
can tell curl the nickname of the certificate to use within the
NSS database defined by the environment variable SSL_DIR (or by
default /etc/pki/nssdb). If the NSS PEM PKCS#11 module (lib-
nsspem.so) is available then PEM files may be loaded. If you
want to use a file from the current directory, please precede it
with “./” prefix, in order to avoid confusion with a nickname.
If the nickname contains “:”, it needs to be preceded by “\” so
that it is not recognized as password delimiter. If the nick-
name contains “\”, it needs to be escaped as “\\” so that it is
not recognized as an escape character.

(iOS and Mac OS X only) If curl is built against Secure Trans-
port, then the certificate string can either be the name of a
certificate/private key in the system or user keychain, or the
path to a PKCS#12-encoded certificate and private key. If you
want to use a file from the current directory, please precede it
with “./” prefix, in order to avoid confusion with a nickname.

If this option is used several times, the last one will be used.

–engine <name>
Select the OpenSSL crypto engine to use for cipher operations.
Use –engine list to print a list of build-time supported
engines. Note that not all (or none) of the engines may be
available at run-time.

–environment
(RISC OS ONLY) Sets a range of environment variables, using the
names the -w option supports, to allow easier extraction of use-
ful information after having run curl.

–egd-file <file>
(SSL) Specify the path name to the Entropy Gathering Daemon
socket. The socket is used to seed the random engine for SSL
connections. See also the –random-file option.

–cert-type <type>
(SSL) Tells curl what certificate type the provided certificate
is in. PEM, DER and ENG are recognized types. If not specified,
PEM is assumed.

If this option is used several times, the last one will be used.

–cacert <CA certificate>
(SSL) Tells curl to use the specified certificate file to verify
the peer. The file may contain multiple CA certificates. The
certificate(s) must be in PEM format. Normally curl is built to
use a default file for this, so this option is typically used to
alter that default file.

curl recognizes the environment variable named ‘CURL_CA_BUNDLE’
if it is set, and uses the given path as a path to a CA cert
bundle. This option overrides that variable.

The windows version of curl will automatically look for a CA
certs file named ‘curl-ca-bundle.crt’, either in the same direc-
tory as curl.exe, or in the Current Working Directory, or in any
folder along your PATH.

If curl is built against the NSS SSL library, the NSS PEM
PKCS#11 module (libnsspem.so) needs to be available for this
option to work properly.

If this option is used several times, the last one will be used.

–capath <CA certificate directory>
(SSL) Tells curl to use the specified certificate directory to
verify the peer. Multiple paths can be provided by separating
them with “:” (e.g. “path1:path2:path3”). The certificates must
be in PEM format, and if curl is built against OpenSSL, the
directory must have been processed using the c_rehash utility
supplied with OpenSSL. Using –capath can allow OpenSSL-powered
curl to make SSL-connections much more efficiently than using
–cacert if the –cacert file contains many CA certificates.

If this option is set, the default capath value will be ignored,
and if it is used several times, the last one will be used.

-f, –fail
(HTTP) Fail silently (no output at all) on server errors. This
is mostly done to better enable scripts etc to better deal with
failed attempts. In normal cases when an HTTP server fails to
deliver a document, it returns an HTML document stating so
(which often also describes why and more). This flag will pre-
vent curl from outputting that and return error 22.

This method is not fail-safe and there are occasions where non-
successful response codes will slip through, especially when
authentication is involved (response codes 401 and 407).

-F, –form <name=content>
(HTTP) This lets curl emulate a filled-in form in which a user
has pressed the submit button. This causes curl to POST data
using the Content-Type multipart/form-data according to RFC
2388. This enables uploading of binary files etc. To force the
‘content’ part to be a file, prefix the file name with an @
sign. To just get the content part from a file, prefix the file
name with the symbol <. The difference between @ and < is then
that @ makes a file get attached in the post as a file upload,
while the < makes a text field and just get the contents for
that text field from a file.

Example, to send your password file to the server, where ‘pass-
word’ is the name of the form-field to which /etc/passwd will be
the input:

curl -F password=@/etc/passwd www.mypasswords.com

To read content from stdin instead of a file, use – as the file-
name. This goes for both @ and < constructs.

You can also tell curl what Content-Type to use by using
‘type=’, in a manner similar to:

curl -F “web=@index.html;type=text/html” url.com

or

curl -F “name=daniel;type=text/foo” url.com

You can also explicitly change the name field of a file upload
part by setting filename=, like this:

curl -F “file=@localfile;filename=nameinpost” url.com

If filename/path contains ‘,’ or ‘;’, it must be quoted by dou-
ble-quotes like:

curl -F “file=@\”localfile\”;filename=\”nameinpost\”” url.com

or

curl -F ‘file=@”localfile”;filename=”nameinpost”‘ url.com

Note that if a filename/path is quoted by double-quotes, any
double-quote or backslash within the filename must be escaped by
backslash.

See further examples and details in the MANUAL.

This option can be used multiple times.

–ftp-account [data]
(FTP) When an FTP server asks for “account data” after user name
and password has been provided, this data is sent off using the
ACCT command. (Added in 7.13.0)

If this option is used several times, the last one will be used.

–ftp-alternative-to-user <command>
(FTP) If authenticating with the USER and PASS commands fails,
send this command. When connecting to Tumbleweed’s Secure
Transport server over FTPS using a client certificate, using
“SITE AUTH” will tell the server to retrieve the username from
the certificate. (Added in 7.15.5)

–ftp-create-dirs
(FTP/SFTP) When an FTP or SFTP URL/operation uses a path that
doesn’t currently exist on the server, the standard behavior of
curl is to fail. Using this option, curl will instead attempt to
create missing directories.

–ftp-method [method]
(FTP) Control what method curl should use to reach a file on an
FTP(S) server. The method argument should be one of the follow-
ing alternatives:

multicwd
curl does a single CWD operation for each path part in
the given URL. For deep hierarchies this means very many
commands. This is how RFC 1738 says it should be done.
This is the default but the slowest behavior.

nocwd curl does no CWD at all. curl will do SIZE, RETR, STOR
etc and give a full path to the server for all these com-
mands. This is the fastest behavior.

singlecwd
curl does one CWD with the full target directory and then
operates on the file “normally” (like in the multicwd
case). This is somewhat more standards compliant than
‘nocwd’ but without the full penalty of ‘multicwd’.
(Added in 7.15.1)

–ftp-pasv
(FTP) Use passive mode for the data connection. Passive is the
internal default behavior, but using this option can be used to
override a previous -P/-ftp-port option. (Added in 7.11.0)

If this option is used several times, only the first one is
used. Undoing an enforced passive really isn’t doable but you
must then instead enforce the correct -P, –ftp-port again.

Passive mode means that curl will try the EPSV command first and
then PASV, unless –disable-epsv is used.

–ftp-skip-pasv-ip
(FTP) Tell curl to not use the IP address the server suggests in
its response to curl’s PASV command when curl connects the data
connection. Instead curl will re-use the same IP address it
already uses for the control connection. (Added in 7.14.2)

This option has no effect if PORT, EPRT or EPSV is used instead
of PASV.

–ftp-pret
(FTP) Tell curl to send a PRET command before PASV (and EPSV).
Certain FTP servers, mainly drftpd, require this non-standard
command for directory listings as well as up and downloads in
PASV mode. (Added in 7.20.x)

–ftp-ssl-ccc
(FTP) Use CCC (Clear Command Channel) Shuts down the SSL/TLS
layer after authenticating. The rest of the control channel com-
munication will be unencrypted. This allows NAT routers to fol-
low the FTP transaction. The default mode is passive. See –ftp-
ssl-ccc-mode for other modes. (Added in 7.16.1)

–ftp-ssl-ccc-mode [active/passive]
(FTP) Use CCC (Clear Command Channel) Sets the CCC mode. The
passive mode will not initiate the shutdown, but instead wait
for the server to do it, and will not reply to the shutdown from
the server. The active mode initiates the shutdown and waits for
a reply from the server. (Added in 7.16.2)

–ftp-ssl-control
(FTP) Require SSL/TLS for the FTP login, clear for transfer.
Allows secure authentication, but non-encrypted data transfers
for efficiency. Fails the transfer if the server doesn’t sup-
port SSL/TLS. (Added in 7.16.0) that can still be used but will
be removed in a future version.

–form-string <name=string>
(HTTP) Similar to –form except that the value string for the
named parameter is used literally. Leading ‘@’ and ‘<‘ charac-
ters, and the ‘;type=’ string in the value have no special mean-
ing. Use this in preference to –form if there’s any possibility
that the string value may accidentally trigger the ‘@’ or ‘<‘
features of –form.

-g, –globoff
This option switches off the “URL globbing parser”. When you set
this option, you can specify URLs that contain the letters {}[]
without having them being interpreted by curl itself. Note that
these letters are not normal legal URL contents but they should
be encoded according to the URI standard.

-G, –get
When used, this option will make all data specified with -d,
–data, –data-binary or –data-urlencode to be used in an HTTP
GET request instead of the POST request that otherwise would be
used. The data will be appended to the URL with a ‘?’ separator.
If used in combination with -I, the POST data will instead be
appended to the URL with a HEAD request.

If this option is used several times, only the first one is
used. This is because undoing a GET doesn’t make sense, but you
should then instead enforce the alternative method you prefer.

-H, –header <header>
(HTTP) Extra header to use when getting a web page. You may
specify any number of extra headers. Note that if you should add
a custom header that has the same name as one of the internal
ones curl would use, your externally set header will be used
instead of the internal one. This allows you to make even trick-
ier stuff than curl would normally do. You should not replace
internally set headers without knowing perfectly well what
you’re doing. Remove an internal header by giving a replacement
without content on the right side of the colon, as in: -H
“Host:”. If you send the custom header with no-value then its
header must be terminated with a semicolon, such as -H “X-Cus-
tom-Header;” to send “X-Custom-Header:”.

curl will make sure that each header you add/replace is sent
with the proper end-of-line marker, you should thus not add that
as a part of the header content: do not add newlines or carriage
returns, they will only mess things up for you.

See also the -A, –user-agent and -e, –referer options.

This option can be used multiple times to add/replace/remove
multiple headers.

–hostpubmd5 <md5>
(SCP/SFTP) Pass a string containing 32 hexadecimal digits. The
string should be the 128 bit MD5 checksum of the remote host’s
public key, curl will refuse the connection with the host unless
the md5sums match. (Added in 7.17.1)

–ignore-content-length
(HTTP) Ignore the Content-Length header. This is particularly
useful for servers running Apache 1.x, which will report incor-
rect Content-Length for files larger than 2 gigabytes.

-i, –include
(HTTP) Include the HTTP-header in the output. The HTTP-header
includes things like server-name, date of the document, HTTP-
version and more…

-I, –head
(HTTP/FTP/FILE) Fetch the HTTP-header only! HTTP-servers feature
the command HEAD which this uses to get nothing but the header
of a document. When used on an FTP or FILE file, curl displays
the file size and last modification time only.

–interface <name>
Perform an operation using a specified interface. You can enter
interface name, IP address or host name. An example could look
like:

curl –interface eth0:1 http://www.netscape.com/

If this option is used several times, the last one will be used.

-j, –junk-session-cookies
(HTTP) When curl is told to read cookies from a given file, this
option will make it discard all “session cookies”. This will
basically have the same effect as if a new session is started.
Typical browsers always discard session cookies when they’re
closed down.

-J, –remote-header-name
(HTTP) This option tells the -O, –remote-name option to use the
server-specified Content-Disposition filename instead of
extracting a filename from the URL.

There’s no attempt to decode %-sequences (yet) in the provided
file name, so this option may provide you with rather unexpected
file names.

-k, –insecure
(SSL) This option explicitly allows curl to perform “insecure”
SSL connections and transfers. All SSL connections are attempted
to be made secure by using the CA certificate bundle installed
by default. This makes all connections considered “insecure”
fail unless -k, –insecure is used.

See this online resource for further details:
http://curl.haxx.se/docs/sslcerts.html

-K, –config <config file>
Specify which config file to read curl arguments from. The con-
fig file is a text file in which command line arguments can be
written which then will be used as if they were written on the
actual command line.

Options and their parameters must be specified on the same con-
fig file line, separated by whitespace, colon, or the equals
sign. Long option names can optionally be given in the config
file without the initial double dashes and if so, the colon or
equals characters can be used as separators. If the option is
specified with one or two dashes, there can be no colon or
equals character between the option and its parameter.

If the parameter is to contain whitespace, the parameter must be
enclosed within quotes. Within double quotes, the following
escape sequences are available: \\, \”, \t, \n, \r and \v. A
backslash preceding any other letter is ignored. If the first
column of a config line is a ‘#’ character, the rest of the line
will be treated as a comment. Only write one option per physical
line in the config file.

Specify the filename to -K, –config as ‘-‘ to make curl read
the file from stdin.

Note that to be able to specify a URL in the config file, you
need to specify it using the –url option, and not by simply
writing the URL on its own line. So, it could look similar to
this:

url = “http://curl.haxx.se/docs/”

When curl is invoked, it always (unless -q is used) checks for a
default config file and uses it if found. The default config
file is checked for in the following places in this order:

1) curl tries to find the “home dir”: It first checks for the
CURL_HOME and then the HOME environment variables. Failing that,
it uses getpwuid() on UNIX-like systems (which returns the home
dir given the current user in your system). On Windows, it then
checks for the APPDATA variable, or as a last resort the ‘%USER-
PROFILE%\Application Data’.

2) On windows, if there is no _curlrc file in the home dir, it
checks for one in the same dir the curl executable is placed. On
UNIX-like systems, it will simply try to load .curlrc from the
determined home dir.

# — Example file —
# this is a comment
url = “curl.haxx.se”
output = “curlhere.html”
user-agent = “superagent/1.0”

# and fetch another URL too
url = “curl.haxx.se/docs/manpage.html”
-O
referer = “http://nowhereatall.com/”
# — End of example file —

This option can be used multiple times to load multiple config
files.

–keepalive-time <seconds>
This option sets the time a connection needs to remain idle
before sending keepalive probes and the time between individual
keepalive probes. It is currently effective on operating systems
offering the TCP_KEEPIDLE and TCP_KEEPINTVL socket options
(meaning Linux, recent AIX, HP-UX and more). This option has no
effect if –no-keepalive is used. (Added in 7.18.0)

If this option is used several times, the last one will be used.
If unspecified, the option defaults to 60 seconds.

–key <key>
(SSL/SSH) Private key file name. Allows you to provide your pri-
vate key in this separate file.

If this option is used several times, the last one will be used.

–key-type <type>
(SSL) Private key file type. Specify which type your –key pro-
vided private key is. DER, PEM, and ENG are supported. If not
specified, PEM is assumed.

If this option is used several times, the last one will be used.

–krb <level>
(FTP) Enable Kerberos authentication and use. The level must be
entered and should be one of ‘clear’, ‘safe’, ‘confidential’, or
‘private’. Should you use a level that is not one of these,
‘private’ will instead be used.

This option requires a library built with kerberos4 or GSSAPI
(GSS-Negotiate) support. This is not very common. Use -V, –ver-
sion to see if your curl supports it.

If this option is used several times, the last one will be used.

-l, –list-only
(FTP) When listing an FTP directory, this switch forces a name-
only view. This is especially useful if the user wants to
machine-parse the contents of an FTP directory since the normal
directory view doesn’t use a standard look or format. When used
like this, the option causes a NLST command to be sent to the
server instead of LIST.

Note: Some FTP servers list only files in their response to
NLST; they do not include sub-directories and symbolic links.

(POP3) When retrieving a specific email from POP3, this switch
forces a LIST command to be performed instead of RETR. This is
particularly useful if the user wants to see if a specific mes-
sage id exists on the server and what size it is.

Note: When combined with -X, –request <command>, this option
can be used to send an UIDL command instead, so the user may use
the email’s unique identifier rather than it’s message id to
make the request. (Added in 7.21.5)

-L, –location
(HTTP/HTTPS) If the server reports that the requested page has
moved to a different location (indicated with a Location: header
and a 3XX response code), this option will make curl redo the
request on the new place. If used together with -i, –include or
-I, –head, headers from all requested pages will be shown. When
authentication is used, curl only sends its credentials to the
initial host. If a redirect takes curl to a different host, it
won’t be able to intercept the user+password. See also –loca-
tion-trusted on how to change this. You can limit the amount of
redirects to follow by using the –max-redirs option.

When curl follows a redirect and the request is not a plain GET
(for example POST or PUT), it will do the following request with
a GET if the HTTP response was 301, 302, or 303. If the response
code was any other 3xx code, curl will re-send the following
request using the same unmodified method.

–libcurl <file>
Append this option to any ordinary curl command line, and you
will get a libcurl-using C source code written to the file that
does the equivalent of what your command-line operation does!

If this option is used several times, the last given file name
will be used. (Added in 7.16.1)

–limit-rate <speed>
Specify the maximum transfer rate you want curl to use. This
feature is useful if you have a limited pipe and you’d like your
transfer not to use your entire bandwidth.

The given speed is measured in bytes/second, unless a suffix is
appended. Appending ‘k’ or ‘K’ will count the number as kilo-
bytes, ‘m’ or M’ makes it megabytes, while ‘g’ or ‘G’ makes it
gigabytes. Examples: 200K, 3m and 1G.

The given rate is the average speed counted during the entire
transfer. It means that curl might use higher transfer speeds in
short bursts, but over time it uses no more than the given rate.
If you also use the -Y, –speed-limit option, that option will
take precedence and might cripple the rate-limiting slightly, to
help keeping the speed-limit logic working.

If this option is used several times, the last one will be used.

–local-port <num>[-num]
Set a preferred number or range of local port numbers to use for
the connection(s). Note that port numbers by nature are a
scarce resource that will be busy at times so setting this range
to something too narrow might cause unnecessary connection setup
failures. (Added in 7.15.2)

–location-trusted
(HTTP/HTTPS) Like -L, –location, but will allow sending the
name + password to all hosts that the site may redirect to. This
may or may not introduce a security breach if the site redirects
you to a site to which you’ll send your authentication info
(which is plaintext in the case of HTTP Basic authentication).

-m, –max-time <seconds>
Maximum time in seconds that you allow the whole operation to
take. This is useful for preventing your batch jobs from hang-
ing for hours due to slow networks or links going down. Since
7.32.0, this option accepts decimal values, but the actual time-
out will decrease in accuracy as the specified timeout increases
in decimal precision. See also the –connect-timeout option.

If this option is used several times, the last one will be used.

–mail-auth <address>
(SMTP) Specify a single address. This will be used to specify
the authentication address (identity) of a submitted message
that is being relayed to another server.

(Added in 7.25.0)

–mail-from <address>
(SMTP) Specify a single address that the given mail should get
sent from.

(Added in 7.20.0)

–max-filesize <bytes>
Specify the maximum size (in bytes) of a file to download. If
the file requested is larger than this value, the transfer will
not start and curl will return with exit code 63.

NOTE: The file size is not always known prior to download, and
for such files this option has no effect even if the file trans-
fer ends up being larger than this given limit. This concerns
both FTP and HTTP transfers.

–mail-rcpt <address>
(SMTP) Specify a single address, user name or mailing list name.
When performing a mail transfer, the recipient should specify a
valid email address to send the mail to. (Added in 7.20.0)

When performing an address verification (VRFY command), the
recipient should be specified as the user name or user name and
domain (as per Section 3.5 of RFC5321). (Added in 7.34.0)

When performing a mailing list expand (EXPN command), the recip-
ient should be specified using the mailing list name, such as
“Friends” or “London-Office”. (Added in 7.34.0)

–max-redirs <num>
Set maximum number of redirection-followings allowed. If -L,
–location is used, this option can be used to prevent curl from
following redirections “in absurdum”. By default, the limit is
set to 50 redirections. Set this option to -1 to make it limit-
less.

If this option is used several times, the last one will be used.

–metalink
This option can tell curl to parse and process a given URI as
Metalink file (both version 3 and 4 (RFC 5854) are supported)
and make use of the mirrors listed within for failover if there
are errors (such as the file or server not being available). It
will also verify the hash of the file after the download com-
pletes. The Metalink file itself is downloaded and processed in
memory and not stored in the local file system.

Example to use a remote Metalink file:

curl –metalink http://www.example.com/example.metalink

To use a Metalink file in the local file system, use FILE proto-
col (file://):

curl –metalink file://example.metalink

Please note that if FILE protocol is disabled, there is no way
to use a local Metalink file at the time of this writing. Also
note that if –metalink and –include are used together,
–include will be ignored. This is because including headers in
the response will break Metalink parser and if the headers are
included in the file described in Metalink file, hash check will
fail.

(Added in 7.27.0, if built against the libmetalink library.)

-n, –netrc
Makes curl scan the .netrc (_netrc on Windows) file in the
user’s home directory for login name and password. This is typi-
cally used for FTP on UNIX. If used with HTTP, curl will enable
user authentication. See netrc(4) or ftp(1) for details on the
file format. Curl will not complain if that file doesn’t have
the right permissions (it should not be either world- or group-
readable). The environment variable “HOME” is used to find the
home directory.

A quick and very simple example of how to setup a .netrc to
allow curl to FTP to the machine host.domain.com with user name
‘myself’ and password ‘secret’ should look similar to:

machine host.domain.com login myself password secret

-N, –no-buffer
Disables the buffering of the output stream. In normal work sit-
uations, curl will use a standard buffered output stream that
will have the effect that it will output the data in chunks, not
necessarily exactly when the data arrives. Using this option
will disable that buffering.

Note that this is the negated option name documented. You can
thus use –buffer to enforce the buffering.

–netrc-file
This option is similar to –netrc, except that you provide the
path (absolute or relative) to the netrc file that Curl should
use. You can only specify one netrc file per invocation. If
several –netrc-file options are provided, only the last one
will be used. (Added in 7.21.5)

This option overrides any use of –netrc as they are mutually
exclusive. It will also abide by –netrc-optional if specified.

–netrc-optional
Very similar to –netrc, but this option makes the .netrc usage
optional and not mandatory as the –netrc option does.

–negotiate
(HTTP) Enables GSS-Negotiate authentication. The GSS-Negotiate
method was designed by Microsoft and is used in their web appli-
cations. It is primarily meant as a support for Kerberos5
authentication but may be also used along with another authenti-
cation method. For more information see IETF draft draft-brezak-
spnego-http-04.txt.

If you want to enable Negotiate for your proxy authentication,
then use –proxy-negotiate.

This option requires a library built with GSSAPI support. This
is not very common. Use -V, –version to see if your version
supports GSS-Negotiate.

When using this option, you must also provide a fake -u, –user
option to activate the authentication code properly. Sending a
‘-u :’ is enough as the user name and password from the -u
option aren’t actually used.

If this option is used several times, only the first one is
used.

–no-keepalive
Disables the use of keepalive messages on the TCP connection, as
by default curl enables them.

Note that this is the negated option name documented. You can
thus use –keepalive to enforce keepalive.

–no-sessionid
(SSL) Disable curl’s use of SSL session-ID caching. By default
all transfers are done using the cache. Note that while nothing
should ever get hurt by attempting to reuse SSL session-IDs,
there seem to be broken SSL implementations in the wild that may
require you to disable this in order for you to succeed. (Added
in 7.16.0)

Note that this is the negated option name documented. You can
thus use –sessionid to enforce session-ID caching.

–noproxy <no-proxy-list>
Comma-separated list of hosts which do not use a proxy, if one
is specified. The only wildcard is a single * character, which
matches all hosts, and effectively disables the proxy. Each name
in this list is matched as either a domain which contains the
hostname, or the hostname itself. For example, local.com would
match local.com, local.com:80, and www.local.com, but not
www.notlocal.com. (Added in 7.19.4).

–ntlm (HTTP) Enables NTLM authentication. The NTLM authentication
method was designed by Microsoft and is used by IIS web servers.
It is a proprietary protocol, reverse-engineered by clever peo-
ple and implemented in curl based on their efforts. This kind of
behavior should not be endorsed, you should encourage everyone
who uses NTLM to switch to a public and documented authentica-
tion method instead, such as Digest.

If you want to enable NTLM for your proxy authentication, then
use –proxy-ntlm.

This option requires a library built with SSL support. Use -V,
–version to see if your curl supports NTLM.

If this option is used several times, only the first one is
used.

-o, –output <file>
Write output to <file> instead of stdout. If you are using {} or
[] to fetch multiple documents, you can use ‘#’ followed by a
number in the <file> specifier. That variable will be replaced
with the current string for the URL being fetched. Like in:

curl http://{one,two}.site.com -o “file_#1.txt”

or use several variables like:

curl http://{site,host}.host[1-5].com -o “#1_#2”

You may use this option as many times as the number of URLs you
have.

See also the –create-dirs option to create the local directo-
ries dynamically. Specifying the output as ‘-‘ (a single dash)
will force the output to be done to stdout.

-O, –remote-name
Write output to a local file named like the remote file we get.
(Only the file part of the remote file is used, the path is cut
off.)

The remote file name to use for saving is extracted from the
given URL, nothing else.

Consequentially, the file will be saved in the current working
directory. If you want the file saved in a different directory,
make sure you change current working directory before you invoke
curl with the -O, –remote-name flag!

There is no URL decoding done on the file name. If it has %20 or
other URL encoded parts of the name, they will end up as-is as
file name.

You may use this option as many times as the number of URLs you
have.

–oauth2-bearer
(IMAP, POP3, SMTP) Specify the Bearer Token for OAUTH 2.0 server
authentication. The Bearer Token is used in conjunction with the
user name which can be specified as part of the –url or -u,
–user options.

The Bearer Token and user name are formatted according to RFC
6750.

If this option is used several times, the last one will be used.

-p, –proxytunnel
When an HTTP proxy is used (-x, –proxy), this option will cause
non-HTTP protocols to attempt to tunnel through the proxy
instead of merely using it to do HTTP-like operations. The tun-
nel approach is made with the HTTP proxy CONNECT request and
requires that the proxy allows direct connect to the remote port
number curl wants to tunnel through to.

-P, –ftp-port <address>
(FTP) Reverses the default initiator/listener roles when con-
necting with FTP. This switch makes curl use active mode. In
practice, curl then tells the server to connect back to the
client’s specified address and port, while passive mode asks the
server to setup an IP address and port for it to connect to.
<address> should be one of:

interface
i.e “eth0” to specify which interface’s IP address you
want to use (Unix only)

IP address
i.e “192.168.10.1” to specify the exact IP address

host name
i.e “my.host.domain” to specify the machine

– make curl pick the same IP address that is already used
for the control connection

If this option is used several times, the last one will be used. Dis-
able the use of PORT with –ftp-pasv. Disable the attempt to use the
EPRT command instead of PORT by using –disable-eprt. EPRT is really
PORT++.

Starting in 7.19.5, you can append “:[start]-[end]” to the right of the
address, to tell curl what TCP port range to use. That means you spec-
ify a port range, from a lower to a higher number. A single number
works as well, but do note that it increases the risk of failure since
the port may not be available.

–pass <phrase>
(SSL/SSH) Passphrase for the private key

If this option is used several times, the last one will be used.

–post301
(HTTP) Tells curl to respect RFC 2616/10.3.2 and not convert
POST requests into GET requests when following a 301 redirect-
ion. The non-RFC behaviour is ubiquitous in web browsers, so
curl does the conversion by default to maintain consistency.
However, a server may require a POST to remain a POST after such
a redirection. This option is meaningful only when using -L,
–location (Added in 7.17.1)

–post302
(HTTP) Tells curl to respect RFC 2616/10.3.2 and not convert
POST requests into GET requests when following a 302 redirect-
ion. The non-RFC behaviour is ubiquitous in web browsers, so
curl does the conversion by default to maintain consistency.
However, a server may require a POST to remain a POST after such
a redirection. This option is meaningful only when using -L,
–location (Added in 7.19.1)

–post303
(HTTP) Tells curl to respect RFC 2616/10.3.2 and not convert
POST requests into GET requests when following a 303 redirect-
ion. The non-RFC behaviour is ubiquitous in web browsers, so
curl does the conversion by default to maintain consistency.
However, a server may require a POST to remain a POST after such
a redirection. This option is meaningful only when using -L,
–location (Added in 7.26.0)

–proto <protocols>
Tells curl to use the listed protocols for its initial
retrieval. Protocols are evaluated left to right, are comma sep-
arated, and are each a protocol name or ‘all’, optionally pre-
fixed by zero or more modifiers. Available modifiers are:

+ Permit this protocol in addition to protocols already permit-
ted (this is the default if no modifier is used).

– Deny this protocol, removing it from the list of protocols
already permitted.

= Permit only this protocol (ignoring the list already permit-
ted), though subject to later modification by subsequent
entries in the comma separated list.

For example:

–proto -ftps uses the default protocols, but disables ftps

–proto -all,https,+http
only enables http and https

–proto =http,https
also only enables http and https

Unknown protocols produce a warning. This allows scripts to
safely rely on being able to disable potentially dangerous pro-
tocols, without relying upon support for that protocol being
built into curl to avoid an error.

This option can be used multiple times, in which case the effect
is the same as concatenating the protocols into one instance of
the option.

(Added in 7.20.2)

–proto-redir <protocols>
Tells curl to use the listed protocols after a redirect. See
–proto for how protocols are represented.

(Added in 7.20.2)

–proxy-anyauth
Tells curl to pick a suitable authentication method when commu-
nicating with the given proxy. This might cause an extra
request/response round-trip. (Added in 7.13.2)

–proxy-basic
Tells curl to use HTTP Basic authentication when communicating
with the given proxy. Use –basic for enabling HTTP Basic with a
remote host. Basic is the default authentication method curl
uses with proxies.

–proxy-digest
Tells curl to use HTTP Digest authentication when communicating
with the given proxy. Use –digest for enabling HTTP Digest with
a remote host.

–proxy-negotiate
Tells curl to use HTTP Negotiate authentication when communicat-
ing with the given proxy. Use –negotiate for enabling HTTP
Negotiate with a remote host. (Added in 7.17.1)

–proxy-ntlm
Tells curl to use HTTP NTLM authentication when communicating
with the given proxy. Use –ntlm for enabling NTLM with a remote
host.

–proxy1.0 <proxyhost[:port]>
Use the specified HTTP 1.0 proxy. If the port number is not
specified, it is assumed at port 1080.

The only difference between this and the HTTP proxy option (-x,
–proxy), is that attempts to use CONNECT through the proxy will
specify an HTTP 1.0 protocol instead of the default HTTP 1.1.

–pubkey <key>
(SSH) Public key file name. Allows you to provide your public
key in this separate file.

If this option is used several times, the last one will be used.

-q If used as the first parameter on the command line, the curlrc
config file will not be read and used. See the -K, –config for
details on the default config file search path.

-Q, –quote <command>
(FTP/SFTP) Send an arbitrary command to the remote FTP or SFTP
server. Quote commands are sent BEFORE the transfer takes place
(just after the initial PWD command in an FTP transfer, to be
exact). To make commands take place after a successful transfer,
prefix them with a dash ‘-‘. To make commands be sent after
curl has changed the working directory, just before the transfer
command(s), prefix the command with a ‘+’ (this is only sup-
ported for FTP). You may specify any number of commands. If the
server returns failure for one of the commands, the entire oper-
ation will be aborted. You must send syntactically correct FTP
commands as RFC 959 defines to FTP servers, or one of the com-
mands listed below to SFTP servers. This option can be used
multiple times. When speaking to an FTP server, prefix the com-
mand with an asterisk (*) to make curl continue even if the com-
mand fails as by default curl will stop at first failure.

SFTP is a binary protocol. Unlike for FTP, curl interprets SFTP
quote commands itself before sending them to the server. File
names may be quoted shell-style to embed spaces or special char-
acters. Following is the list of all supported SFTP quote com-
mands:

chgrp group file
The chgrp command sets the group ID of the file named by
the file operand to the group ID specified by the group
operand. The group operand is a decimal integer group ID.

chmod mode file
The chmod command modifies the file mode bits of the
specified file. The mode operand is an octal integer mode
number.

chown user file
The chown command sets the owner of the file named by the
file operand to the user ID specified by the user oper-
and. The user operand is a decimal integer user ID.

ln source_file target_file
The ln and symlink commands create a symbolic link at the
target_file location pointing to the source_file loca-
tion.

mkdir directory_name
The mkdir command creates the directory named by the
directory_name operand.

pwd The pwd command returns the absolute pathname of the cur-
rent working directory.

rename source target
The rename command renames the file or directory named by
the source operand to the destination path named by the
target operand.

rm file
The rm command removes the file specified by the file op-
erand.

rmdir directory
The rmdir command removes the directory entry specified
by the directory operand, provided it is empty.

symlink source_file target_file
See ln.

-r, –range <range>
(HTTP/FTP/SFTP/FILE) Retrieve a byte range (i.e a partial docu-
ment) from a HTTP/1.1, FTP or SFTP server or a local FILE.
Ranges can be specified in a number of ways.

0-499 specifies the first 500 bytes

500-999 specifies the second 500 bytes

-500 specifies the last 500 bytes

9500- specifies the bytes from offset 9500 and forward

0-0,-1 specifies the first and last byte only(*)(H)

500-700,600-799
specifies 300 bytes from offset 500(H)

100-199,500-599
specifies two separate 100-byte ranges(*)(H)

(*) = NOTE that this will cause the server to reply with a multipart
response!

Only digit characters (0-9) are valid in the ‘start’ and ‘stop’ fields
of the ‘start-stop’ range syntax. If a non-digit character is given in
the range, the server’s response will be unspecified, depending on the
server’s configuration.

You should also be aware that many HTTP/1.1 servers do not have this
feature enabled, so that when you attempt to get a range, you’ll
instead get the whole document.

FTP and SFTP range downloads only support the simple ‘start-stop’ syn-
tax (optionally with one of the numbers omitted). FTP use depends on
the extended FTP command SIZE.

If this option is used several times, the last one will be used.

-R, –remote-time
When used, this will make curl attempt to figure out the time-
stamp of the remote file, and if that is available make the
local file get that same timestamp.

–random-file <file>
(SSL) Specify the path name to file containing what will be con-
sidered as random data. The data is used to seed the random
engine for SSL connections. See also the –egd-file option.

–raw (HTTP) When used, it disables all internal HTTP decoding of con-
tent or transfer encodings and instead makes them passed on
unaltered, raw. (Added in 7.16.2)

–remote-name-all
This option changes the default action for all given URLs to be
dealt with as if -O, –remote-name were used for each one. So if
you want to disable that for a specific URL after –remote-name-
all has been used, you must use “-o -” or –no-remote-name.
(Added in 7.19.0)

–resolve <host:port:address>
Provide a custom address for a specific host and port pair.
Using this, you can make the curl requests(s) use a specified
address and prevent the otherwise normally resolved address to
be used. Consider it a sort of /etc/hosts alternative provided
on the command line. The port number should be the number used
for the specific protocol the host will be used for. It means
you need several entries if you want to provide address for the
same host but different ports.

This option can be used many times to add many host names to
resolve.

(Added in 7.21.3)

–retry <num>
If a transient error is returned when curl tries to perform a
transfer, it will retry this number of times before giving up.
Setting the number to 0 makes curl do no retries (which is the
default). Transient error means either: a timeout, an FTP 4xx
response code or an HTTP 5xx response code.

When curl is about to retry a transfer, it will first wait one
second and then for all forthcoming retries it will double the
waiting time until it reaches 10 minutes which then will be the
delay between the rest of the retries. By using –retry-delay
you disable this exponential backoff algorithm. See also
–retry-max-time to limit the total time allowed for retries.
(Added in 7.12.3)

If this option is used several times, the last one will be used.

–retry-delay <seconds>
Make curl sleep this amount of time before each retry when a
transfer has failed with a transient error (it changes the
default backoff time algorithm between retries). This option is
only interesting if –retry is also used. Setting this delay to
zero will make curl use the default backoff time. (Added in
7.12.3)

If this option is used several times, the last one will be used.

–retry-max-time <seconds>
The retry timer is reset before the first transfer attempt.
Retries will be done as usual (see –retry) as long as the timer
hasn’t reached this given limit. Notice that if the timer hasn’t
reached the limit, the request will be made and while perform-
ing, it may take longer than this given time period. To limit a
single request’s maximum time, use -m, –max-time. Set this
option to zero to not timeout retries. (Added in 7.12.3)

If this option is used several times, the last one will be used.

-s, –silent
Silent or quiet mode. Don’t show progress meter or error mes-
sages. Makes Curl mute. It will still output the data you ask
for, potentially even to the terminal/stdout unless you redirect
it.

–sasl-ir
Enable initial response in SASL authentication. (Added in
7.31.0)

-S, –show-error
When used with -s it makes curl show an error message if it
fails.

–ssl (FTP, POP3, IMAP, SMTP) Try to use SSL/TLS for the connection.
Reverts to a non-secure connection if the server doesn’t support
SSL/TLS. See also –ftp-ssl-control and –ssl-reqd for differ-
ent levels of encryption required. (Added in 7.20.0)

This option was formerly known as –ftp-ssl (Added in 7.11.0).
That option name can still be used but will be removed in a
future version.

–ssl-reqd
(FTP, POP3, IMAP, SMTP) Require SSL/TLS for the connection.
Terminates the connection if the server doesn’t support SSL/TLS.
(Added in 7.20.0)

This option was formerly known as –ftp-ssl-reqd (added in
7.15.5). That option name can still be used but will be removed
in a future version.

–ssl-allow-beast
(SSL) This option tells curl to not work around a security flaw
in the SSL3 and TLS1.0 protocols known as BEAST. If this option
isn’t used, the SSL layer may use work-arounds known to cause
interoperability problems with some older SSL implementations.
WARNING: this option loosens the SSL security, and by using this
flag you ask for exactly that. (Added in 7.25.0)

–socks4 <host[:port]>
Use the specified SOCKS4 proxy. If the port number is not speci-
fied, it is assumed at port 1080. (Added in 7.15.2)

This option overrides any previous use of -x, –proxy, as they
are mutually exclusive.

Since 7.21.7, this option is superfluous since you can specify a
socks4 proxy with -x, –proxy using a socks4:// protocol prefix.
If this option is used several times, the last one will be used.

–socks4a <host[:port]>
Use the specified SOCKS4a proxy. If the port number is not spec-
ified, it is assumed at port 1080. (Added in 7.18.0)

This option overrides any previous use of -x, –proxy, as they
are mutually exclusive.

Since 7.21.7, this option is superfluous since you can specify a
socks4a proxy with -x, –proxy using a socks4a:// protocol pre-
fix.

If this option is used several times, the last one will be used.

–socks5-hostname <host[:port]>
Use the specified SOCKS5 proxy (and let the proxy resolve the
host name). If the port number is not specified, it is assumed
at port 1080. (Added in 7.18.0)

This option overrides any previous use of -x, –proxy, as they
are mutually exclusive.

Since 7.21.7, this option is superfluous since you can specify a
socks5 hostname proxy with -x, –proxy using a socks5h:// proto-
col prefix.

If this option is used several times, the last one will be used.
(This option was previously wrongly documented and used as
–socks without the number appended.)

–socks5 <host[:port]>
Use the specified SOCKS5 proxy – but resolve the host name
locally. If the port number is not specified, it is assumed at
port 1080.

This option overrides any previous use of -x, –proxy, as they
are mutually exclusive.

Since 7.21.7, this option is superfluous since you can specify a
socks5 proxy with -x, –proxy using a socks5:// protocol prefix.
If this option is used several times, the last one will be used.
(This option was previously wrongly documented and used as
–socks without the number appended.)

This option (as well as –socks4) does not work with IPV6, FTPS
or LDAP.

–socks5-gssapi-service <servicename>
The default service name for a socks server is rcmd/server-fqdn.
This option allows you to change it.

Examples: –socks5 proxy-name –socks5-gssapi-service sockd
would use sockd/proxy-name –socks5 proxy-name –socks5-gssapi-
service sockd/real-name would use sockd/real-name for cases
where the proxy-name does not match the principal name. (Added
in 7.19.4).

–socks5-gssapi-nec
As part of the gssapi negotiation a protection mode is negoti-
ated. RFC 1961 says in section 4.3/4.4 it should be protected,
but the NEC reference implementation does not. The option
–socks5-gssapi-nec allows the unprotected exchange of the pro-
tection mode negotiation. (Added in 7.19.4).

–stderr <file>
Redirect all writes to stderr to the specified file instead. If
the file name is a plain ‘-‘, it is instead written to stdout.

If this option is used several times, the last one will be used.

-t, –telnet-option <OPT=val>
Pass options to the telnet protocol. Supported options are:

TTYPE=<term> Sets the terminal type.

XDISPLOC=<X display> Sets the X display location.

NEW_ENV=<var,val> Sets an environment variable.

-T, –upload-file <file>
This transfers the specified local file to the remote URL. If
there is no file part in the specified URL, Curl will append the
local file name. NOTE that you must use a trailing / on the last
directory to really prove to Curl that there is no file name or
curl will think that your last directory name is the remote file
name to use. That will most likely cause the upload operation to
fail. If this is used on an HTTP(S) server, the PUT command will
be used.

Use the file name “-” (a single dash) to use stdin instead of a
given file. Alternately, the file name “.” (a single period)
may be specified instead of “-” to use stdin in non-blocking
mode to allow reading server output while stdin is being
uploaded.

You can specify one -T for each URL on the command line. Each -T
+ URL pair specifies what to upload and to where. curl also sup-
ports “globbing” of the -T argument, meaning that you can upload
multiple files to a single URL by using the same URL globbing
style supported in the URL, like this:

curl -T “{file1,file2}” http://www.uploadtothissite.com

or even

curl -T “img[1-1000].png” ftp://ftp.picturemania.com/upload/

–tcp-nodelay
Turn on the TCP_NODELAY option. See the curl_easy_setopt(3) man
page for details about this option. (Added in 7.11.2)

–tftp-blksize <value>
(TFTP) Set TFTP BLKSIZE option (must be >512). This is the block
size that curl will try to use when transferring data to or from
a TFTP server. By default 512 bytes will be used.

If this option is used several times, the last one will be used.

(Added in 7.20.0)

–tlsauthtype <authtype>
Set TLS authentication type. Currently, the only supported
option is “SRP”, for TLS-SRP (RFC 5054). If –tlsuser and
–tlspassword are specified but –tlsauthtype is not, then this
option defaults to “SRP”. (Added in 7.21.4)

–tlspassword <password>
Set password for use with the TLS authentication method speci-
fied with –tlsauthtype. Requires that –tlsuser also be set.
(Added in 7.21.4)

–tlsuser <user>
Set username for use with the TLS authentication method speci-
fied with –tlsauthtype. Requires that –tlspassword also be
set. (Added in 7.21.4)

–tlsv1.0
(SSL) Forces curl to use TLS version 1.0 when negotiating with a
remote TLS server. (Added in 7.34.0)

–tlsv1.1
(SSL) Forces curl to use TLS version 1.1 when negotiating with a
remote TLS server. (Added in 7.34.0)

–tlsv1.2
(SSL) Forces curl to use TLS version 1.2 when negotiating with a
remote TLS server. (Added in 7.34.0)

–tr-encoding
(HTTP) Request a compressed Transfer-Encoding response using one
of the algorithms curl supports, and uncompress the data while
receiving it.

(Added in 7.21.6)

–trace <file>
Enables a full trace dump of all incoming and outgoing data,
including descriptive information, to the given output file. Use
“-” as filename to have the output sent to stdout.

This option overrides previous uses of -v, –verbose or –trace-
ascii.

If this option is used several times, the last one will be used.

–trace-ascii <file>
Enables a full trace dump of all incoming and outgoing data,
including descriptive information, to the given output file. Use
“-” as filename to have the output sent to stdout.

This is very similar to –trace, but leaves out the hex part and
only shows the ASCII part of the dump. It makes smaller output
that might be easier to read for untrained humans.

This option overrides previous uses of -v, –verbose or –trace.
If this option is used several times, the last one will be used.

–trace-time
Prepends a time stamp to each trace or verbose line that curl
displays. (Added in 7.14.0)

-u, –user <user:password;options>
Specify the user name, password and optional login options to
use for server authentication. Overrides -n, –netrc and
–netrc-optional.

If you simply specify the user name, with or without the login
options, curl will prompt for a password.

If you use an SSPI-enabled curl binary and perform NTLM authen-
tication, you can force curl to select the user name and pass-
word from your environment by simply specifying a single colon
with this option: “-u :” or by specfying the login options on
their own, for example “-u ;auth=NTLM”.

You can use the optional login options part to specify protocol
specific options that may be used during authentication. At
present only IMAP, POP3 and SMTP support login options as part
of the user login information. For more information about the
login options please see RFC 2384, RFC 5092 and IETF draft
draft-earhart-url-smtp-00.txt (Added in 7.31.0).

If this option is used several times, the last one will be used.

-U, –proxy-user <user:password>
Specify the user name and password to use for proxy authentica-
tion.

If you use an SSPI-enabled curl binary and do NTLM authentica-
tion, you can force curl to pick up the user name and password
from your environment by simply specifying a single colon with
this option: “-U :”.

If this option is used several times, the last one will be used.

–url <URL>
Specify a URL to fetch. This option is mostly handy when you
want to specify URL(s) in a config file.

This option may be used any number of times. To control where
this URL is written, use the -o, –output or the -O, –remote-
name options.
-v, –verbose
Makes the fetching more verbose/talkative. Mostly useful for
debugging. A line starting with ‘>’ means “header data” sent by
curl, ‘<‘ means “header data” received by curl that is hidden in
normal cases, and a line starting with ‘*’ means additional info
provided by curl.

Note that if you only want HTTP headers in the output, -i,
–include might be the option you’re looking for.

If you think this option still doesn’t give you enough details,
consider using –trace or –trace-ascii instead.

This option overrides previous uses of –trace-ascii or –trace.

Use -s, –silent to make curl quiet.

-w, –write-out <format>
Defines what to display on stdout after a completed and success-
ful operation. The format is a string that may contain plain
text mixed with any number of variables. The string can be spec-
ified as “string”, to get read from a particular file you spec-
ify it “@filename” and to tell curl to read the format from
stdin you write “@-“.

The variables present in the output format will be substituted
by the value or text that curl thinks fit, as described below.
All variables are specified as %{variable_name} and to output a
normal % you just write them as %%. You can output a newline by
using \n, a carriage return with \r and a tab space with \t.

NOTE: The %-symbol is a special symbol in the win32-environment,
where all occurrences of % must be doubled when using this
option.

The variables available are:

content_type The Content-Type of the requested document, if
there was any.

filename_effective
The ultimate filename that curl writes out to.
This is only meaningful if curl is told to write
to a file with the –remote-name or –output
option. It’s most useful in combination with the
–remote-header-name option. (Added in 7.25.1)

ftp_entry_path The initial path curl ended up in when logging on
to the remote FTP server. (Added in 7.15.4)

http_code The numerical response code that was found in the
last retrieved HTTP(S) or FTP(s) transfer. In
7.18.2 the alias response_code was added to show
the same info.

http_connect The numerical code that was found in the last
response (from a proxy) to a curl CONNECT
request. (Added in 7.12.4)

local_ip The IP address of the local end of the most
recently done connection – can be either IPv4 or
IPv6 (Added in 7.29.0)

local_port The local port number of the most recently done
connection (Added in 7.29.0)

num_connects Number of new connects made in the recent trans-
fer. (Added in 7.12.3)

num_redirects Number of redirects that were followed in the
request. (Added in 7.12.3)

redirect_url When an HTTP request was made without -L to fol-
low redirects, this variable will show the actual
URL a redirect would take you to. (Added in
7.18.2)

remote_ip The remote IP address of the most recently done
connection – can be either IPv4 or IPv6 (Added in
7.29.0)

remote_port The remote port number of the most recently done
connection (Added in 7.29.0)

size_download The total amount of bytes that were downloaded.

size_header The total amount of bytes of the downloaded head-
ers.

size_request The total amount of bytes that were sent in the
HTTP request.

size_upload The total amount of bytes that were uploaded.

speed_download The average download speed that curl measured for
the complete download. Bytes per second.

speed_upload The average upload speed that curl measured for
the complete upload. Bytes per second.

ssl_verify_result
The result of the SSL peer certificate verifica-
tion that was requested. 0 means the verification
was successful. (Added in 7.19.0)

time_appconnect
The time, in seconds, it took from the start
until the SSL/SSH/etc connect/handshake to the
remote host was completed. (Added in 7.19.0)

time_connect The time, in seconds, it took from the start
until the TCP connect to the remote host (or
proxy) was completed.

time_namelookup
The time, in seconds, it took from the start
until the name resolving was completed.

time_pretransfer
The time, in seconds, it took from the start
until the file transfer was just about to begin.
This includes all pre-transfer commands and nego-
tiations that are specific to the particular pro-
tocol(s) involved.

time_redirect The time, in seconds, it took for all redirection
steps include name lookup, connect, pretransfer
and transfer before the final transaction was
started. time_redirect shows the complete execu-
tion time for multiple redirections. (Added in
7.12.3)

time_starttransfer
The time, in seconds, it took from the start
until the first byte was just about to be trans-
ferred. This includes time_pretransfer and also
the time the server needed to calculate the
result.

time_total The total time, in seconds, that the full opera-
tion lasted. The time will be displayed with mil-
lisecond resolution.

url_effective The URL that was fetched last. This is most mean-
ingful if you’ve told curl to follow location:
headers.

If this option is used several times, the last one will be used.

-x, –proxy <[protocol://][user:password@]proxyhost[:port]>
Use the specified proxy.

The proxy string can be specified with a protocol:// prefix to
specify alternative proxy protocols. Use socks4://, socks4a://,
socks5:// or socks5h:// to request the specific SOCKS version to
be used. No protocol specified, http:// and all others will be
treated as HTTP proxies. (The protocol support was added in curl
7.21.7)

If the port number is not specified in the proxy string, it is
assumed to be 1080.

This option overrides existing environment variables that set
the proxy to use. If there’s an environment variable setting a
proxy, you can set proxy to “” to override it.

All operations that are performed over an HTTP proxy will trans-
parently be converted to HTTP. It means that certain protocol
specific operations might not be available. This is not the case
if you can tunnel through the proxy, as one with the -p, –prox-
ytunnel option.

User and password that might be provided in the proxy string are
URL decoded by curl. This allows you to pass in special charac-
ters such as @ by using %40 or pass in a colon with %3a.

The proxy host can be specified the exact same way as the proxy
environment variables, including the protocol prefix (http://)
and the embedded user + password.

If this option is used several times, the last one will be used.

-X, –request <command>
(HTTP) Specifies a custom request method to use when communicat-
ing with the HTTP server. The specified request will be used
instead of the method otherwise used (which defaults to GET).
Read the HTTP 1.1 specification for details and explanations.
Common additional HTTP requests include PUT and DELETE, but
related technologies like WebDAV offers PROPFIND, COPY, MOVE and
more.

Normally you don’t need this option. All sorts of GET, HEAD,
POST and PUT requests are rather invoked by using dedicated com-
mand line options.

This option only changes the actual word used in the HTTP
request, it does not alter the way curl behaves. So for example
if you want to make a proper HEAD request, using -X HEAD will
not suffice. You need to use the -I, –head option.

(FTP) Specifies a custom FTP command to use instead of LIST when
doing file lists with FTP.

(POP3) Specifies a custom POP3 command to use instead of LIST or
RETR. (Added in 7.26.0)

(IMAP) Specifies a custom IMAP command to use insead of LIST.
(Added in 7.30.0)

(SMTP) Specifies a custom SMTP command to use instead of HELP or
VRFY. (Added in 7.34.0)

If this option is used several times, the last one will be used.

–xattr
When saving output to a file, this option tells curl to store
certain file metadata in extended file attributes. Currently,
the URL is stored in the xdg.origin.url attribute and, for HTTP,
the content type is stored in the mime_type attribute. If the
file system does not support extended attributes, a warning is
issued.

-y, –speed-time <time>
If a download is slower than speed-limit bytes per second during
a speed-time period, the download gets aborted. If speed-time is
used, the default speed-limit will be 1 unless set with -Y.

This option controls transfers and thus will not affect slow
connects etc. If this is a concern for you, try the –connect-
timeout option.

If this option is used several times, the last one will be used.

-Y, –speed-limit <speed>
If a download is slower than this given speed (in bytes per sec-
ond) for speed-time seconds it gets aborted. speed-time is set
with -y and is 30 if not set.

If this option is used several times, the last one will be used.

-z, –time-cond <date expression>|<file>
(HTTP/FTP) Request a file that has been modified later than the
given time and date, or one that has been modified before that
time. The <date expression> can be all sorts of date strings or
if it doesn’t match any internal ones, it is taken as a filename
and tries to get the modification date (mtime) from <file>
instead. See the curl_getdate(3) man pages for date expression
details.

Start the date expression with a dash (-) to make it request for
a document that is older than the given date/time, default is a
document that is newer than the specified date/time.

If this option is used several times, the last one will be used.

-h, –help
Usage help.

-M, –manual
Manual. Display the huge help text.

-V, –version
Displays information about curl and the libcurl version it uses.
The first line includes the full version of curl, libcurl and
other 3rd party libraries linked with the executable.

The second line (starts with “Protocols:”) shows all protocols
that libcurl reports to support.

The third line (starts with “Features:”) shows specific features
libcurl reports to offer. Available features include:

IPv6 You can use IPv6 with this.

krb4 Krb4 for FTP is supported.

SSL HTTPS and FTPS are supported.

libz Automatic decompression of compressed files over HTTP is
supported.

NTLM NTLM authentication is supported.

GSS-Negotiate
Negotiate authentication and krb5 for FTP is supported.

Debug This curl uses a libcurl built with Debug. This enables
more error-tracking and memory debugging etc. For curl-
developers only!

AsynchDNS
This curl uses asynchronous name resolves.

SPNEGO SPNEGO Negotiate authentication is supported.

Largefile
This curl supports transfers of large files, files larger
than 2GB.

IDN This curl supports IDN – international domain names.

SSPI SSPI is supported. If you use NTLM and set a blank user
name, curl will authenticate with your current user and
password.

TLS-SRP
SRP (Secure Remote Password) authentication is supported
for TLS.
Metalink
This curl supports Metalink (both version 3 and 4 (RFC
5854)), which describes mirrors and hashes. curl will
use mirrors for failover if there are errors (such as the
file or server not being available).

FILES
~/.curlrc
Default config file, see -K, –config for details.

ENVIRONMENT
The environment variables can be specified in lower case or upper case.
The lower case version has precedence. http_proxy is an exception as it
is only available in lower case.

Using an environment variable to set the proxy has the same effect as
using the –proxy option.

http_proxy [protocol://]<host>[:port]
Sets the proxy server to use for HTTP.
HTTPS_PROXY [protocol://]<host>[:port]
Sets the proxy server to use for HTTPS.

[url-protocol]_PROXY [protocol://]<host>[:port]
Sets the proxy server to use for [url-protocol], where the pro-
tocol is a protocol that curl supports and as specified in a
URL. FTP, FTPS, POP3, IMAP, SMTP, LDAP etc.

ALL_PROXY [protocol://]<host>[:port]
Sets the proxy server to use if no protocol-specific proxy is
set.

NO_PROXY <comma-separated list of hosts>
list of host names that shouldn’t go through any proxy. If set
to a asterisk ‘*’ only, it matches all hosts.

PROXY PROTOCOL PREFIXES
Since curl version 7.21.7, the proxy string may be specified with a
protocol:// prefix to specify alternative proxy protocols.

If no protocol is specified in the proxy string or if the string
doesn’t match a supported one, the proxy will be treated as an HTTP
proxy.

The supported proxy protocol prefixes are as follows:

socks4://
Makes it the equivalent of –socks4

socks4a://
Makes it the equivalent of –socks4a

socks5://
Makes it the equivalent of –socks5

socks5h://
Makes it the equivalent of –socks5-hostname

EXIT CODES
There are a bunch of different error codes and their corresponding
error messages that may appear during bad conditions. At the time of
this writing, the exit codes are:

1 Unsupported protocol. This build of curl has no support for this
protocol.

2 Failed to initialize.

3 URL malformed. The syntax was not correct.

4 A feature or option that was needed to perform the desired
request was not enabled or was explicitly disabled at build-
time. To make curl able to do this, you probably need another
build of libcurl!

5 Couldn’t resolve proxy. The given proxy host could not be
resolved.

6 Couldn’t resolve host. The given remote host was not resolved.

7 Failed to connect to host.

8 FTP weird server reply. The server sent data curl couldn’t
parse.

9 FTP access denied. The server denied login or denied access to
the particular resource or directory you wanted to reach. Most
often you tried to change to a directory that doesn’t exist on
the server.

11 FTP weird PASS reply. Curl couldn’t parse the reply sent to the
PASS request.

13 FTP weird PASV reply, Curl couldn’t parse the reply sent to the
PASV request.

14 FTP weird 227 format. Curl couldn’t parse the 227-line the
server sent.

15 FTP can’t get host. Couldn’t resolve the host IP we got in the
227-line.

17 FTP couldn’t set binary. Couldn’t change transfer method to
binary.

18 Partial file. Only a part of the file was transferred.

19 FTP couldn’t download/access the given file, the RETR (or simi-
lar) command failed.

21 FTP quote error. A quote command returned error from the server.
22 HTTP page not retrieved. The requested url was not found or
returned another error with the HTTP error code being 400 or
above. This return code only appears if -f, –fail is used.

23 Write error. Curl couldn’t write data to a local filesystem or
similar.

25 FTP couldn’t STOR file. The server denied the STOR operation,
used for FTP uploading.

26 Read error. Various reading problems.

27 Out of memory. A memory allocation request failed.

28 Operation timeout. The specified time-out period was reached
according to the conditions.

30 FTP PORT failed. The PORT command failed. Not all FTP servers
support the PORT command, try doing a transfer using PASV
instead!

31 FTP couldn’t use REST. The REST command failed. This command is
used for resumed FTP transfers.

33 HTTP range error. The range “command” didn’t work.

34 HTTP post error. Internal post-request generation error.

35 SSL connect error. The SSL handshaking failed.

36 FTP bad download resume. Couldn’t continue an earlier aborted
download.

37 FILE couldn’t read file. Failed to open the file. Permissions?

38 LDAP cannot bind. LDAP bind operation failed.

39 LDAP search failed.

41 Function not found. A required LDAP function was not found.

42 Aborted by callback. An application told curl to abort the oper-
ation.

43 Internal error. A function was called with a bad parameter.

45 Interface error. A specified outgoing interface could not be
used.

47 Too many redirects. When following redirects, curl hit the maxi-
mum amount.

48 Unknown option specified to libcurl. This indicates that you
passed a weird option to curl that was passed on to libcurl and
rejected. Read up in the manual!

49 Malformed telnet option.

51 The peer’s SSL certificate or SSH MD5 fingerprint was not OK.

52 The server didn’t reply anything, which here is considered an
error.

53 SSL crypto engine not found.

54 Cannot set SSL crypto engine as default.

55 Failed sending network data.

56 Failure in receiving network data.

58 Problem with the local certificate.

59 Couldn’t use specified SSL cipher.

60 Peer certificate cannot be authenticated with known CA certifi-
cates.

61 Unrecognized transfer encoding.

62 Invalid LDAP URL.

63 Maximum file size exceeded.

64 Requested FTP SSL level failed.

65 Sending the data requires a rewind that failed.

66 Failed to initialise SSL Engine.

67 The user name, password, or similar was not accepted and curl
failed to log in.

68 File not found on TFTP server.

69 Permission problem on TFTP server.

70 Out of disk space on TFTP server.

71 Illegal TFTP operation.

72 Unknown TFTP transfer ID.

73 File already exists (TFTP).

74 No such user (TFTP).

75 Character conversion failed.

76 Character conversion functions required.

77 Problem with reading the SSL CA cert (path? access rights?).

78 The resource referenced in the URL does not exist.

79 An unspecified error occurred during the SSH session.

80 Failed to shut down the SSL connection.

82 Could not load CRL file, missing or wrong format (added in
7.19.0).

83 Issuer check failed (added in 7.19.0).

84 The FTP PRET command failed

85 RTSP: mismatch of CSeq numbers

86 RTSP: mismatch of Session Identifiers

87 unable to parse FTP file list

88 FTP chunk callback reported error

89 No connection available, the session will be queued

XX More error codes will appear here in future releases. The exist-
ing ones are meant to never change.

AUTHORS / CONTRIBUTORS
Daniel Stenberg is the main author, but the whole list of contributors
is found in the separate THANKS file.

WWW
http://curl.haxx.se

FTP
ftp://ftp.sunet.se/pub/www/utilities/curl/

SEE ALSO
ftp(1), wget(1)

LATEST VERSION

You always find news about what’s going on as well as the latest versions
from the curl web pages, located at:

http://curl.haxx.se

SIMPLE USAGE

Get the main page from Netscape’s web-server:

curl http://www.netscape.com/

Get the README file the user’s home directory at funet’s ftp-server:

curl ftp://ftp.funet.fi/README

Get a web page from a server using port 8000:

curl http://www.weirdserver.com:8000/

Get a directory listing of an FTP site:

curl ftp://cool.haxx.se/

Get the definition of curl from a dictionary:

curl dict://dict.org/m:curl

Fetch two documents at once:

curl ftp://cool.haxx.se/ http://www.weirdserver.com:8000/

Get a file off an FTPS server:

curl ftps://files.are.secure.com/secrets.txt

or use the more appropriate FTPS way to get the same file:

curl –ftp-ssl ftp://files.are.secure.com/secrets.txt

Get a file from an SSH server using SFTP:

curl -u username sftp://shell.example.com/etc/issue

Get a file from an SSH server using SCP using a private key to authenticate:

curl -u username: –key ~/.ssh/id_dsa –pubkey ~/.ssh/id_dsa.pub \
scp://shell.example.com/~/personal.txt

Get the main page from an IPv6 web server:

curl -g “http://[2001:1890:1112:1::20]/”

DOWNLOAD TO A FILE

Get a web page and store in a local file with a specific name:

curl -o thatpage.html http://www.netscape.com/

Get a web page and store in a local file, make the local file get the name
of the remote document (if no file name part is specified in the URL, this
will fail):

curl -O http://www.netscape.com/index.html

Fetch two files and store them with their remote names:

curl -O www.haxx.se/index.html -O curl.haxx.se/download.html

USING PASSWORDS

FTP

To ftp files using name+passwd, include them in the URL like:

curl ftp://name:passwd@machine.domain:port/full/path/to/file

or specify them with the -u flag like

curl -u name:passwd ftp://machine.domain:port/full/path/to/file

FTPS

It is just like for FTP, but you may also want to specify and use
SSL-specific options for certificates etc.

Note that using FTPS:// as prefix is the “implicit” way as described in the
standards while the recommended “explicit” way is done by using FTP:// and
the –ftp-ssl option.

SFTP / SCP

This is similar to FTP, but you can specify a private key to use instead of
a password. Note that the private key may itself be protected by a password
that is unrelated to the login password of the remote system. If you
provide a private key file you must also provide a public key file.

HTTP

Curl also supports user and password in HTTP URLs, thus you can pick a file
like:

curl http://name:passwd@machine.domain/full/path/to/file

or specify user and password separately like in

curl -u name:passwd http://machine.domain/full/path/to/file

HTTP offers many different methods of authentication and curl supports
several: Basic, Digest, NTLM and Negotiate. Without telling which method to
use, curl defaults to Basic. You can also ask curl to pick the most secure
ones out of the ones that the server accepts for the given URL, by using
–anyauth.

NOTE! According to the URL specification, HTTP URLs can not contain a user
and password, so that style will not work when using curl via a proxy, even
though curl allows it at other times. When using a proxy, you _must_ use
the -u style for user and password.

HTTPS

Probably most commonly used with private certificates, as explained below.

PROXY

curl supports both HTTP and SOCKS proxy servers, with optional authentication.
It does not have special support for FTP proxy servers since there are no
standards for those, but it can still be made to work with many of them. You
can also use both HTTP and SOCKS proxies to transfer files to and from FTP
servers.

Get an ftp file using an HTTP proxy named my-proxy that uses port 888:

curl -x my-proxy:888 ftp://ftp.leachsite.com/README

Get a file from an HTTP server that requires user and password, using the
same proxy as above:

curl -u user:passwd -x my-proxy:888 http://www.get.this/

Some proxies require special authentication. Specify by using -U as above:

curl -U user:passwd -x my-proxy:888 http://www.get.this/

A comma-separated list of hosts and domains which do not use the proxy can
be specified as:

curl –noproxy localhost,get.this -x my-proxy:888 http://www.get.this/

If the proxy is specified with –proxy1.0 instead of –proxy or -x, then
curl will use HTTP/1.0 instead of HTTP/1.1 for any CONNECT attempts.

curl also supports SOCKS4 and SOCKS5 proxies with –socks4 and –socks5.

See also the environment variables Curl supports that offer further proxy
control.

Most FTP proxy servers are set up to appear as a normal FTP server from the
client’s perspective, with special commands to select the remote FTP server.
curl supports the -u, -Q and –ftp-account options that can be used to
set up transfers through many FTP proxies. For example, a file can be
uploaded to a remote FTP server using a Blue Coat FTP proxy with the
options:

curl -u “Remote-FTP-Username@remote.ftp.server Proxy-Username:Remote-Pass” \
–ftp-account Proxy-Password –upload-file local-file \
ftp://my-ftp.proxy.server:21/remote/upload/path/

See the manual for your FTP proxy to determine the form it expects to set up
transfers, and curl’s -v option to see exactly what curl is sending.

RANGES

HTTP 1.1 introduced byte-ranges. Using this, a client can request
to get only one or more subparts of a specified document. Curl supports
this with the -r flag.

Get the first 100 bytes of a document:

curl -r 0-99 http://www.get.this/

Get the last 500 bytes of a document:

curl -r -500 http://www.get.this/

Curl also supports simple ranges for FTP files as well. Then you can only
specify start and stop position.

Get the first 100 bytes of a document using FTP:

curl -r 0-99 ftp://www.get.this/README

UPLOADING

FTP / FTPS / SFTP / SCP

Upload all data on stdin to a specified server:

curl -T – ftp://ftp.upload.com/myfile

Upload data from a specified file, login with user and password:

curl -T uploadfile -u user:passwd ftp://ftp.upload.com/myfile

Upload a local file to the remote site, and use the local file name at the remote
site too:

curl -T uploadfile -u user:passwd ftp://ftp.upload.com/

Upload a local file to get appended to the remote file:

curl -T localfile -a ftp://ftp.upload.com/remotefile

Curl also supports ftp upload through a proxy, but only if the proxy is
configured to allow that kind of tunneling. If it does, you can run curl in
a fashion similar to:

curl –proxytunnel -x proxy:port -T localfile ftp.upload.com

HTTP

Upload all data on stdin to a specified HTTP site:

curl -T – http://www.upload.com/myfile

Note that the HTTP server must have been configured to accept PUT before
this can be done successfully.

For other ways to do HTTP data upload, see the POST section below.

VERBOSE / DEBUG

If curl fails where it isn’t supposed to, if the servers don’t let you in,
if you can’t understand the responses: use the -v flag to get verbose
fetching. Curl will output lots of info and what it sends and receives in
order to let the user see all client-server interaction (but it won’t show
you the actual data).

curl -v ftp://ftp.upload.com/

To get even more details and information on what curl does, try using the
–trace or –trace-ascii options with a given file name to log to, like
this:

curl –trace trace.txt www.haxx.se
DETAILED INFORMATION

Different protocols provide different ways of getting detailed information
about specific files/documents. To get curl to show detailed information
about a single file, you should use -I/–head option. It displays all
available info on a single file for HTTP and FTP. The HTTP information is a
lot more extensive.

For HTTP, you can get the header information (the same as -I would show)
shown before the data by using -i/–include. Curl understands the
-D/–dump-header option when getting files from both FTP and HTTP, and it
will then store the headers in the specified file.

Store the HTTP headers in a separate file (headers.txt in the example):

curl –dump-header headers.txt curl.haxx.se

Note that headers stored in a separate file can be very useful at a later
time if you want curl to use cookies sent by the server. More about that in
the cookies section.

POST (HTTP)

It’s easy to post data using curl. This is done using the -d <data>
option. The post data must be urlencoded.

Post a simple “name” and “phone” guestbook.

curl -d “name=Rafael%20Sagula&phone=3320780” \
http://www.where.com/guest.cgi

How to post a form with curl, lesson #1:

Dig out all the <input> tags in the form that you want to fill in. (There’s
a perl program called formfind.pl on the curl site that helps with this).

If there’s a “normal” post, you use -d to post. -d takes a full “post
string”, which is in the format

<variable1>=<data1>&<variable2>=<data2>&…

The ‘variable’ names are the names set with “name=” in the <input> tags, and
the data is the contents you want to fill in for the inputs. The data *must*
be properly URL encoded. That means you replace space with + and that you
replace weird letters with %XX where XX is the hexadecimal representation of
the letter’s ASCII code.

Example:

(page located at http://www.formpost.com/getthis/

<form action=”post.cgi” method=”post”>
<input name=user size=10>
<input name=pass type=password size=10>
<input name=id type=hidden value=”blablabla”>
<input name=ding value=”submit”>
</form>

We want to enter user ‘foobar’ with password ‘12345’.

To post to this, you enter a curl command line like:

curl -d “user=foobar&pass=12345&id=blablabla&ding=submit” (continues)
http://www.formpost.com/getthis/post.cgi
While -d uses the application/x-www-form-urlencoded mime-type, generally
understood by CGI’s and similar, curl also supports the more capable
multipart/form-data type. This latter type supports things like file upload.

-F accepts parameters like -F “name=contents”. If you want the contents to
be read from a file, use <@filename> as contents. When specifying a file,
you can also specify the file content type by appending ‘;type=<mime type>’
to the file name. You can also post the contents of several files in one
field. For example, the field name ‘coolfiles’ is used to send three files,
with different content types using the following syntax:

curl -F “coolfiles=@fil1.gif;type=image/gif,fil2.txt,fil3.html” \
http://www.post.com/postit.cgi

If the content-type is not specified, curl will try to guess from the file
extension (it only knows a few), or use the previously specified type (from
an earlier file if several files are specified in a list) or else it will
use the default type ‘application/octet-stream’.

Emulate a fill-in form with -F. Let’s say you fill in three fields in a
form. One field is a file name which to post, one field is your name and one
field is a file description. We want to post the file we have written named
“cooltext.txt”. To let curl do the posting of this data instead of your
favourite browser, you have to read the HTML source of the form page and
find the names of the input fields. In our example, the input field names
are ‘file’, ‘yourname’ and ‘filedescription’.

curl -F “file=@cooltext.txt” -F “yourname=Daniel” \
-F “filedescription=Cool text file with cool text inside” \
http://www.post.com/postit.cgi

To send two files in one post you can do it in two ways:

1. Send multiple files in a single “field” with a single field name:

curl -F “pictures=@dog.gif,cat.gif”

2. Send two fields with two field names:

curl -F “docpicture=@dog.gif” -F “catpicture=@cat.gif”

To send a field value literally without interpreting a leading ‘@’
or ‘<‘, or an embedded ‘;type=’, use –form-string instead of
-F. This is recommended when the value is obtained from a user or
some other unpredictable source. Under these circumstances, using
-F instead of –form-string would allow a user to trick curl into
uploading a file.

REFERRER

An HTTP request has the option to include information about which address
referred it to the actual page. Curl allows you to specify the
referrer to be used on the command line. It is especially useful to
fool or trick stupid servers or CGI scripts that rely on that information
being available or contain certain data.

curl -e www.coolsite.com http://www.showme.com/

NOTE: The Referer: [sic] field is defined in the HTTP spec to be a full URL.

USER AGENT

An HTTP request has the option to include information about the browser
that generated the request. Curl allows it to be specified on the command
line. It is especially useful to fool or trick stupid servers or CGI
scripts that only accept certain browsers.

Example:

curl -A ‘Mozilla/3.0 (Win95; I)’ http://www.nationsbank.com/

Other common strings:
‘Mozilla/3.0 (Win95; I)’ Netscape Version 3 for Windows 95
‘Mozilla/3.04 (Win95; U)’ Netscape Version 3 for Windows 95
‘Mozilla/2.02 (OS/2; U)’ Netscape Version 2 for OS/2
‘Mozilla/4.04 [en] (X11; U; AIX 4.2; Nav)’ NS for AIX
‘Mozilla/4.05 [en] (X11; U; Linux 2.0.32 i586)’ NS for Linux

Note that Internet Explorer tries hard to be compatible in every way:
‘Mozilla/4.0 (compatible; MSIE 4.01; Windows 95)’ MSIE for W95

Mozilla is not the only possible User-Agent name:
‘Konqueror/1.0’ KDE File Manager desktop client
‘Lynx/2.7.1 libwww-FM/2.14’ Lynx command line browser

COOKIES

Cookies are generally used by web servers to keep state information at the
client’s side. The server sets cookies by sending a response line in the
headers that looks like ‘Set-Cookie: <data>’ where the data part then
typically contains a set of NAME=VALUE pairs (separated by semicolons ‘;’
like “NAME1=VALUE1; NAME2=VALUE2;”). The server can also specify for what
path the “cookie” should be used for (by specifying “path=value”), when the
cookie should expire (“expire=DATE”), for what domain to use it
(“domain=NAME”) and if it should be used on secure connections only
(“secure”).

If you’ve received a page from a server that contains a header like:
Set-Cookie: sessionid=boo123; path=”/foo”;

it means the server wants that first pair passed on when we get anything in
a path beginning with “/foo”.

Example, get a page that wants my name passed in a cookie:

curl -b “name=Daniel” www.sillypage.com

Curl also has the ability to use previously received cookies in following
sessions. If you get cookies from a server and store them in a file in a
manner similar to:

curl –dump-header headers www.example.com

… you can then in a second connect to that (or another) site, use the
cookies from the ‘headers’ file like:

curl -b headers www.example.com

While saving headers to a file is a working way to store cookies, it is
however error-prone and not the preferred way to do this. Instead, make curl
save the incoming cookies using the well-known netscape cookie format like
this:

curl -c cookies.txt www.example.com

Note that by specifying -b you enable the “cookie awareness” and with -L
you can make curl follow a location: (which often is used in combination
with cookies). So that if a site sends cookies and a location, you can
use a non-existing file to trigger the cookie awareness like:

curl -L -b empty.txt www.example.com

The file to read cookies from must be formatted using plain HTTP headers OR
as netscape’s cookie file. Curl will determine what kind it is based on the
file contents. In the above command, curl will parse the header and store
the cookies received from www.example.com. curl will send to the server the
stored cookies which match the request as it follows the location. The
file “empty.txt” may be a nonexistent file.

Alas, to both read and write cookies from a netscape cookie file, you can
set both -b and -c to use the same file:

curl -b cookies.txt -c cookies.txt www.example.com

PROGRESS METER

The progress meter exists to show a user that something actually is
happening. The different fields in the output have the following meaning:

% Total % Received % Xferd Average Speed Time Curr.
Dload Upload Total Current Left Speed
0 151M 0 38608 0 0 9406 0 4:41:43 0:00:04 4:41:39 9287

From left-to-right:
% – percentage completed of the whole transfer
Total – total size of the whole expected transfer
% – percentage completed of the download
Received – currently downloaded amount of bytes
% – percentage completed of the upload
Xferd – currently uploaded amount of bytes
Average Speed
Dload – the average transfer speed of the download
Average Speed
Upload – the average transfer speed of the upload
Time Total – expected time to complete the operation
Time Current – time passed since the invoke
Time Left – expected time left to completion
Curr.Speed – the average transfer speed the last 5 seconds (the first
5 seconds of a transfer is based on less time of course.)

The -# option will display a totally different progress bar that doesn’t
need much explanation!

SPEED LIMIT

Curl allows the user to set the transfer speed conditions that must be met
to let the transfer keep going. By using the switch -y and -Y you
can make curl abort transfers if the transfer speed is below the specified
lowest limit for a specified time.

To have curl abort the download if the speed is slower than 3000 bytes per
second for 1 minute, run:

curl -Y 3000 -y 60 www.far-away-site.com

This can very well be used in combination with the overall time limit, so
that the above operation must be completed in whole within 30 minutes:

curl -m 1800 -Y 3000 -y 60 www.far-away-site.com

Forcing curl not to transfer data faster than a given rate is also possible,
which might be useful if you’re using a limited bandwidth connection and you
don’t want your transfer to use all of it (sometimes referred to as
“bandwidth throttle”).

Make curl transfer data no faster than 10 kilobytes per second:

curl –limit-rate 10K www.far-away-site.com

or

curl –limit-rate 10240 www.far-away-site.com

Or prevent curl from uploading data faster than 1 megabyte per second:

curl -T upload –limit-rate 1M ftp://uploadshereplease.com

When using the –limit-rate option, the transfer rate is regulated on a
per-second basis, which will cause the total transfer speed to become lower
than the given number. Sometimes of course substantially lower, if your
transfer stalls during periods.

CONFIG FILE

Curl automatically tries to read the .curlrc file (or _curlrc file on win32
systems) from the user’s home dir on startup.

The config file could be made up with normal command line switches, but you
can also specify the long options without the dashes to make it more
readable. You can separate the options and the parameter with spaces, or
with = or :. Comments can be used within the file. If the first letter on a
line is a ‘#’-symbol the rest of the line is treated as a comment.

If you want the parameter to contain spaces, you must enclose the entire
parameter within double quotes (“). Within those quotes, you specify a
quote as \”.

NOTE: You must specify options and their arguments on the same line.

Example, set default time out and proxy in a config file:

# We want a 30 minute timeout:
-m 1800
# … and we use a proxy for all accesses:
proxy = proxy.our.domain.com:8080

White spaces ARE significant at the end of lines, but all white spaces
leading up to the first characters of each line are ignored.

Prevent curl from reading the default file by using -q as the first command
line parameter, like:

curl -q www.thatsite.com

Force curl to get and display a local help page in case it is invoked
without URL by making a config file similar to:

# default url to get
url = “http://help.with.curl.com/curlhelp.html”

You can specify another config file to be read by using the -K/–config
flag. If you set config file name to “-” it’ll read the config from stdin,
which can be handy if you want to hide options from being visible in process
tables etc:

echo “user = user:passwd” | curl -K – http://that.secret.site.com

EXTRA HEADERS

When using curl in your own very special programs, you may end up needing
to pass on your own custom headers when getting a web page. You can do
this by using the -H flag.

Example, send the header “X-you-and-me: yes” to the server when getting a
page:

curl -H “X-you-and-me: yes” www.love.com

This can also be useful in case you want curl to send a different text in a
header than it normally does. The -H header you specify then replaces the
header curl would normally send. If you replace an internal header with an
empty one, you prevent that header from being sent. To prevent the Host:
header from being used:

curl -H “Host:” www.server.com

FTP and PATH NAMES

Do note that when getting files with the ftp:// URL, the given path is
relative the directory you enter. To get the file ‘README’ from your home
directory at your ftp site, do:

curl ftp://user:passwd@my.site.com/README

But if you want the README file from the root directory of that very same
site, you need to specify the absolute file name:

curl ftp://user:passwd@my.site.com//README

(I.e with an extra slash in front of the file name.)

SFTP and SCP and PATH NAMES

With sftp: and scp: URLs, the path name given is the absolute name on the
server. To access a file relative to the remote user’s home directory,
prefix the file with /~/ , such as:

curl -u $USER sftp://home.example.com/~/.bashrc

FTP and firewalls

The FTP protocol requires one of the involved parties to open a second
connection as soon as data is about to get transferred. There are two ways to
do this.

The default way for curl is to issue the PASV command which causes the
server to open another port and await another connection performed by the
client. This is good if the client is behind a firewall that doesn’t allow
incoming connections.

curl ftp.download.com

If the server, for example, is behind a firewall that doesn’t allow connections
on ports other than 21 (or if it just doesn’t support the PASV command), the
other way to do it is to use the PORT command and instruct the server to
connect to the client on the given IP number and port (as parameters to the
PORT command).

The -P flag to curl supports a few different options. Your machine may have
several IP-addresses and/or network interfaces and curl allows you to select
which of them to use. Default address can also be used:

curl -P – ftp.download.com

Download with PORT but use the IP address of our ‘le0’ interface (this does
not work on windows):

curl -P le0 ftp.download.com

Download with PORT but use 192.168.0.10 as our IP address to use:

curl -P 192.168.0.10 ftp.download.com

NETWORK INTERFACE

Get a web page from a server using a specified port for the interface:

curl –interface eth0:1 http://www.netscape.com/

or

curl –interface 192.168.1.10 http://www.netscape.com/

HTTPS

Secure HTTP requires SSL libraries to be installed and used when curl is
built. If that is done, curl is capable of retrieving and posting documents
using the HTTPS protocol.

Example:

curl https://www.secure-site.com

Curl is also capable of using your personal certificates to get/post files
from sites that require valid certificates. The only drawback is that the
certificate needs to be in PEM-format. PEM is a standard and open format to
store certificates with, but it is not used by the most commonly used
browsers (Netscape and MSIE both use the so called PKCS#12 format). If you
want curl to use the certificates you use with your (favourite) browser, you
may need to download/compile a converter that can convert your browser’s
formatted certificates to PEM formatted ones. This kind of converter is
included in recent versions of OpenSSL, and for older versions Dr Stephen
N. Henson has written a patch for SSLeay that adds this functionality. You
can get his patch (that requires an SSLeay installation) from his site at:
http://www.drh-consultancy.demon.co.uk/

Example on how to automatically retrieve a document using a certificate with
a personal password:

curl -E /path/to/cert.pem:password https://secure.site.com/

If you neglect to specify the password on the command line, you will be
prompted for the correct password before any data can be received.

Many older SSL-servers have problems with SSLv3 or TLS, which newer versions
of OpenSSL etc use, therefore it is sometimes useful to specify what
SSL-version curl should use. Use -3, -2 or -1 to specify that exact SSL
version to use (for SSLv3, SSLv2 or TLSv1 respectively):

curl -2 https://secure.site.com/

Otherwise, curl will first attempt to use v3 and then v2.

To use OpenSSL to convert your favourite browser’s certificate into a PEM
formatted one that curl can use, do something like this:

In Netscape, you start with hitting the ‘Security’ menu button.

Select ‘certificates->yours’ and then pick a certificate in the list

Press the ‘Export’ button

enter your PIN code for the certs

select a proper place to save it

Run the ‘openssl’ application to convert the certificate. If you cd to the
openssl installation, you can do it like:

# ./apps/openssl pkcs12 -in [file you saved] -clcerts -out [PEMfile]

In Firefox, select Options, then Advanced, then the Encryption tab,
View Certificates. This opens the Certificate Manager, where you can
Export. Be sure to select PEM for the Save as type.

In Internet Explorer, select Internet Options, then the Content tab, then
Certificates. Then you can Export, and depending on the format you may
need to convert to PEM.

In Chrome, select Settings, then Show Advanced Settings. Under HTTPS/SSL
select Manage Certificates.

RESUMING FILE TRANSFERS

To continue a file transfer where it was previously aborted, curl supports
resume on HTTP(S) downloads as well as FTP uploads and downloads.

Continue downloading a document:

curl -C – -o file ftp://ftp.server.com/path/file

Continue uploading a document(*1):

curl -C – -T file ftp://ftp.server.com/path/file

Continue downloading a document from a web server(*2):

curl -C – -o file http://www.server.com/

(*1) = This requires that the FTP server supports the non-standard command
SIZE. If it doesn’t, curl will say so.

(*2) = This requires that the web server supports at least HTTP/1.1. If it
doesn’t, curl will say so.

TIME CONDITIONS

HTTP allows a client to specify a time condition for the document it
requests. It is If-Modified-Since or If-Unmodified-Since. Curl allows you to
specify them with the -z/–time-cond flag.

For example, you can easily make a download that only gets performed if the
remote file is newer than a local copy. It would be made like:

curl -z local.html http://remote.server.com/remote.html

Or you can download a file only if the local file is newer than the remote
one. Do this by prepending the date string with a ‘-‘, as in:

curl -z -local.html http://remote.server.com/remote.html

You can specify a “free text” date as condition. Tell curl to only download
the file if it was updated since January 12, 2012:

curl -z “Jan 12 2012” http://remote.server.com/remote.html

Curl will then accept a wide range of date formats. You always make the date
check the other way around by prepending it with a dash ‘-‘.

DICT

For fun try

curl dict://dict.org/m:curl
curl dict://dict.org/d:heisenbug:jargon
curl dict://dict.org/d:daniel:web1913

Aliases for ‘m’ are ‘match’ and ‘find’, and aliases for ‘d’ are ‘define’
and ‘lookup’. For example,

curl dict://dict.org/find:curl

Commands that break the URL description of the RFC (but not the DICT
protocol) are

curl dict://dict.org/show:db
curl dict://dict.org/show:strat

Authentication is still missing (but this is not required by the RFC)

LDAP

If you have installed the OpenLDAP library, curl can take advantage of it
and offer ldap:// support.

LDAP is a complex thing and writing an LDAP query is not an easy task. I do
advise you to dig up the syntax description for that elsewhere. Two places
that might suit you are:

Netscape’s “Netscape Directory SDK 3.0 for C Programmer’s Guide Chapter 10:
Working with LDAP URLs”:
http://developer.netscape.com/docs/manuals/dirsdk/csdk30/url.htm

RFC 2255, “The LDAP URL Format” http://curl.haxx.se/rfc/rfc2255.txt

To show you an example, this is how I can get all people from my local LDAP
server that has a certain sub-domain in their email address:

curl -B “ldap://ldap.frontec.se/o=frontec??sub?mail=*sth.frontec.se”

If I want the same info in HTML format, I can get it by not using the -B
(enforce ASCII) flag.

ENVIRONMENT VARIABLES

Curl reads and understands the following environment variables:

http_proxy, HTTPS_PROXY, FTP_PROXY

They should be set for protocol-specific proxies. General proxy should be
set with

ALL_PROXY

A comma-separated list of host names that shouldn’t go through any proxy is
set in (only an asterisk, ‘*’ matches all hosts)

NO_PROXY

If the host name matches one of these strings, or the host is within the
domain of one of these strings, transactions with that node will not be
proxied.
The usage of the -x/–proxy flag overrides the environment variables.

NETRC

Unix introduced the .netrc concept a long time ago. It is a way for a user
to specify name and password for commonly visited FTP sites in a file so
that you don’t have to type them in each time you visit those sites. You
realize this is a big security risk if someone else gets hold of your
passwords, so therefore most unix programs won’t read this file unless it is
only readable by yourself (curl doesn’t care though).

Curl supports .netrc files if told to (using the -n/–netrc and
–netrc-optional options). This is not restricted to just FTP,
so curl can use it for all protocols where authentication is used.

A very simple .netrc file could look something like:

machine curl.haxx.se login iamdaniel password mysecret

CUSTOM OUTPUT

To better allow script programmers to get to know about the progress of
curl, the -w/–write-out option was introduced. Using this, you can specify
what information from the previous transfer you want to extract.

To display the amount of bytes downloaded together with some text and an
ending newline:

curl -w ‘We downloaded %{size_download} bytes\n’ www.download.com

KERBEROS FTP TRANSFER

Curl supports kerberos4 and kerberos5/GSSAPI for FTP transfers. You need
the kerberos package installed and used at curl build time for it to be
available.

First, get the krb-ticket the normal way, like with the kinit/kauth tool.
Then use curl in way similar to:

curl –krb private ftp://krb4site.com -u username:fakepwd

There’s no use for a password on the -u switch, but a blank one will make
curl ask for one and you already entered the real password to kinit/kauth.

TELNET

The curl telnet support is basic and very easy to use. Curl passes all data
passed to it on stdin to the remote server. Connect to a remote telnet
server using a command line similar to:

curl telnet://remote.server.com

And enter the data to pass to the server on stdin. The result will be sent
to stdout or to the file you specify with -o.

You might want the -N/–no-buffer option to switch off the buffered output
for slow connections or similar.

Pass options to the telnet protocol negotiation, by using the -t option. To
tell the server we use a vt100 terminal, try something like:

curl -tTTYPE=vt100 telnet://remote.server.com

Other interesting options for it -t include:

– XDISPLOC=<X display> Sets the X display location.

– NEW_ENV=<var,val> Sets an environment variable.

NOTE: The telnet protocol does not specify any way to login with a specified
user and password so curl can’t do that automatically. To do that, you need
to track when the login prompt is received and send the username and
password accordingly.

PERSISTENT CONNECTIONS

Specifying multiple files on a single command line will make curl transfer
all of them, one after the other in the specified order.

libcurl will attempt to use persistent connections for the transfers so that
the second transfer to the same host can use the same connection that was
already initiated and was left open in the previous transfer. This greatly
decreases connection time for all but the first transfer and it makes a far
better use of the network.

Note that curl cannot use persistent connections for transfers that are used
in subsequence curl invokes. Try to stuff as many URLs as possible on the
same command line if they are using the same host, as that’ll make the
transfers faster. If you use an HTTP proxy for file transfers, practically
all transfers will be persistent.

MULTIPLE TRANSFERS WITH A SINGLE COMMAND LINE

As is mentioned above, you can download multiple files with one command line
by simply adding more URLs. If you want those to get saved to a local file
instead of just printed to stdout, you need to add one save option for each
URL you specify. Note that this also goes for the -O option (but not
–remote-name-all).

For example: get two files and use -O for the first and a custom file
name for the second:

curl -O http://url.com/file.txt ftp://ftp.com/moo.exe -o moo.jpg

You can also upload multiple files in a similar fashion:

curl -T local1 ftp://ftp.com/moo.exe -T local2 ftp://ftp.com/moo2.txt

IPv6

curl will connect to a server with IPv6 when a host lookup returns an IPv6
address and fall back to IPv4 if the connection fails. The –ipv4 and –ipv6
options can specify which address to use when both are available. IPv6
addresses can also be specified directly in URLs using the syntax:

http://[2001:1890:1112:1::20]/overview.html

When this style is used, the -g option must be given to stop curl from
interpreting the square brackets as special globbing characters. Link local
and site local addresses including a scope identifier, such as fe80::1234%1,
may also be used, but the scope portion must be numeric and the percent
character must be URL escaped. The previous example in an SFTP URL might
look like:

sftp://[fe80::1234%251]/

IPv6 addresses provided other than in URLs (e.g. to the –proxy, –interface
or –ftp-port options) should not be URL encoded.

METALINK

Curl supports Metalink (both version 3 and 4 (RFC 5854) are supported), a way
to list multiple URIs and hashes for a file. Curl will make use of the mirrors
listed within for failover if there are errors (such as the file or server not
being available). It will also verify the hash of the file after the download
completes. The Metalink file itself is downloaded and processed in memory and
not stored in the local file system.

Example to use a remote Metalink file:

curl –metalink http://www.example.com/example.metalink

To use a Metalink file in the local file system, use FILE protocol (file://):

curl –metalink file://example.metalink

Please note that if FILE protocol is disabled, there is no way to use a local
Metalink file at the time of this writing. Also note that if –metalink and
–include are used together, –include will be ignored. This is because including
headers in the response will break Metalink parser and if the headers are included
in the file described in Metalink file, hash check will fail.

MAILING LISTS

For your convenience, we have several open mailing lists to discuss curl,
its development and things relevant to this. Get all info at
http://curl.haxx.se/mail/. Some of the lists available are:

curl-users

Users of the command line tool. How to use it, what doesn’t work, new
features, related tools, questions, news, installations, compilations,
running, porting etc.

curl-library

Developers using or developing libcurl. Bugs, extensions, improvements.

curl-announce

Low-traffic. Only receives announcements of new public versions. At worst,
that makes something like one or two mails per month, but usually only one
mail every second month.

curl-and-php

Using the curl functions in PHP. Everything curl with a PHP angle. Or PHP
with a curl angle.

curl-and-python

Python hackers using curl with or without the python binding pycurl.

Please direct curl questions, feature requests and trouble reports to one of
these mailing lists instead of mailing any individual.

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