curl Man page

Resume Wikipedia de CURL

cURL (abréviation de client URL request library : « bibliothèque de requêtes aux URL pour les clients » ou see URL : « voir URL ») est une interface en ligne de commande, destinée à récupérer le contenu d’une ressource accessible par un réseau informatique.
La ressource est désignée à l’aide d’une URL et doit être d’un type supporté par le logiciel (voir ci-dessous). Le logiciel permet de créer ou modifier une ressource (contrairement à wget), il peut ainsi être utilisé en tant que client REST.
Le programme cURL implémente l’interface utilisateur et repose sur la bibliothèque logicielle libcurl, développée en langage C. Celle-ci est ainsi accessible aux programmeurs qui veulent disposer des fonctionnalités d’accès au réseau dans leurs programmes. Des interfaces ont été créées dans de nombreux langages (C++, Java, .NET, Perl, PHP, Ruby…).
La bibliothèque supporte notamment les protocoles DICT, file, FTP, FTPS, Gopher, HTTP, HTTPS, IMAP, IMAPS, LDAP, LDAPS, POP3, POP3S, RTSP, SCP, SFTP, SMB, SMBS, SMTP, SMTPS, Telnet et TFTP.
L’écriture peut se faire en HTTP en utilisant les commandes POST ou PUT.

curl Curl Manual curl

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, SMB, SMBS,
SMTP, SMTPS, TELNET and TFTP). The command is designed to work without
user interaction.

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 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

When using [] or {} sequences when invoked from a command line prompt,
you probably have to put the full URL within double quotes to avoid the
shell from interfering with it. This also goes for other characters
treated special, like for example ‘&’, ‘?’ and ‘*’.

Provide the IPv6 zone index in the URL with an escaped percentage sign
and the interface name. Like in

http://[fe80::3%25eth0]/

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
additional value next to them.

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.

-:, –next
Tells curl to use a separate operation for the following URL and
associated options. This allows you to send several URL
requests, each with their own specific options, for example,
such as different user names or custom requests for each. (Added
in 7.36.0)

-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
(HTTP) Tells curl to issue its requests using HTTP 2. This
requires that the underlying libcurl was built to support it.
(Added in 7.33.0)

–no-npn
Disable the NPN TLS extension. NPN is enabled by default if
libcurl was built with an SSL library that supports NPN. NPN is
used by a libcurl that supports HTTP 2 to negotiate HTTP 2 sup‐
port with the server during https sessions.

(Added in 7.36.0)

–no-alpn
Disable the ALPN TLS extension. ALPN is enabled by default if
libcurl was built with an SSL library that supports ALPN. ALPN
is used by a libcurl that supports HTTP 2 to negotiate HTTP 2
support with the server during https sessions.

(Added in 7.36.0)

-1, –tlsv1
(SSL) Forces curl to use TLS version 1.x when negotiating with a
remote TLS server. You can use options –tlsv1.0, –tlsv1.1,
and –tlsv1.2 to control the TLS version more precisely (if the
SSL backend in use supports such a level of control).

-2, –sslv2
(SSL) Forces curl to use SSL version 2 when negotiating with a
remote SSL server. Sometimes curl is built without SSLv2 sup‐
port. SSLv2 is widely considered insecure (see RFC 6176).

-3, –sslv3
(SSL) Forces curl to use SSL version 3 when negotiating with a
remote SSL server. Sometimes curl is built without SSLv3 sup‐
port. SSLv3 is widely considered insecure (see RFC 7568).

-4, –ipv4
This option tells curl to resolve names to IPv4 addresses only,
and not for example try IPv6.

-6, –ipv6
This option tells curl to resolve names to IPv6 addresses only,
and not for example try IPv4.

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

-A, –user-agent
(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
(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 engine 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.

The file specified with -b, –cookie is only used as input. No
cookies will be written to the file. To store cookies, use the
-c, –cookie-jar option.

Exercise caution if you are using this option and multiple
transfers may occur. If you use the NAME1=VALUE1; format, or in
a file use the Set-Cookie format and don’t specify a domain,
then the cookie is sent for any domain (even after redirects are
followed) and cannot be modified by a server-set cookie. If the
cookie engine is enabled and a server sets a cookie of the same
name then both will be sent on a future transfer to that server,
likely not what you intended. To address these issues set a
domain in Set-Cookie (doing that will include sub-domains) or
use the Netscape format.

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 with the
remote host. 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 –negotiate).

Used together with -u, –user and -x, –proxy.

See also –proxy-basic.

-c, –cookie-jar
(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 data 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.

Since 7.43.0 cookies that were imported in the Set-Cookie format
without a domain name are not exported by this option.

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

-C, –continue-at
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 (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:
https://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: https://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
Maximum time in seconds that you allow curl’s connection to
take. This only limits the connection phase, so if curl con‐
nects within the given period it will continue – if not it will
exit. Since version 7.32.0, this option accepts decimal values.

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

(SMTP added in 7.40.0)

–crlfile
(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
(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. –data-raw is almost the
same but does not have a special interpretation of the @ charac‐
ter. 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. If you
don’t want the @ character to have a special interpretation use
–data-raw instead.

-D, –dump-header
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 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
See -d, –data.

–data-binary
(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-raw
(HTTP) This posts data similarly to –data but without the spe‐
cial interpretation of the @ character. See -d, –data. (Added
in 7.43.0)

–data-urlencode
(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 part should begin with a name
followed by a separator and a content specification. The
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
Tell curl to send outgoing DNS requests through .
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
Tell curl to bind to 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
Tell curl to bind to 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
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 : 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
(HTTP) Sends the “Referrer 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
(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 client certificate concatenated!
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
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
(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.

–expect100-timeout
(HTTP) Maximum time in seconds that you allow curl to wait for a
100-continue response when curl emits an Expects: 100-continue
header in its request. By default curl will wait one second.
This option accepts decimal values! When curl stops waiting, it
will continue as if the response has been received.

(Added in 7.47.0)

–cert-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
(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
(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.

–pinnedpubkey (SSL) Tells curl to use the specified public key file (or
hashes) to verify the peer. This can be a path to a file which
contains a single public key in PEM or DER format, or any number
of base64 encoded sha256 hashes preceded by ´sha256//´ and sepa‐
rated by ´;´

When negotiating a TLS or SSL connection, the server sends a
certificate indicating its identity. A public key is extracted
from this certificate and if it does not exactly match the pub‐
lic key provided to this option, curl will abort the connection
before sending or receiving any data.

Added in 7.39.0 for OpenSSL, GnuTLS and GSKit. Added in 7.43.0
for NSS and wolfSSL/CyaSSL. sha256 support added in 7.44.0 for
OpenSSL, GnuTLS, NSS and wolfSSL/CyaSSL. Other SSL backends not
supported.

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

–cert-status
(SSL) Tells curl to verify the status of the server certificate
by using the Certificate Status Request (aka. OCSP stapling) TLS
extension.

If this option is enabled and the server sends an invalid (e.g.
expired) response, if the response suggests that the server cer‐
tificate has been revoked, or no response at all is received,
the verification fails.

This is currently only implemented in the OpenSSL, GnuTLS and
NSS backends. (Added in 7.41.0)

–false-start

(SSL) Tells curl to use false start during the TLS handshake.
False start is a mode where a TLS client will start sending
application data before verifying the server’s Finished message,
thus saving a round trip when performing a full handshake.

This is currently only implemented in the NSS and Secure Trans‐
port (on iOS 7.0 or later, or OS X 10.9 or later) backends.
(Added in 7.42.0)

-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
(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. Unfortunately it does not support reading the file from a named pipe or similar, as it needs the full size before the transfer starts. 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
(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
(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

(HTTP) Extra header to include in the request when sending HTTP
to a server. 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 trickier stuff than curl would normally do. You
should not replace internally set headers without knowing per‐
fectly well what you’re doing. Remove an internal header by giv‐
ing 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-Custom-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.

Starting in 7.37.0, you need –proxy-header to send custom head‐
ers intended for a proxy.

Example:

# curl -H “X-First-Name: Joe” http://192.168.0.1/

WARNING: headers set with this option will be set in all
requests – even after redirects are followed, like when told
with -L, –location. This can lead to the header being sent to
other hosts than the original host, so sensitive headers should
be used with caution combined with following redirects.

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

–hostpubmd5
(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
For 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.

For FTP (since 7.46.0), skip the RETR command to figure out the
size before downloading a file.

-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
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
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
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
(SSL/SSH) Private key file name. Allows you to provide your pri‐
vate key in this separate file. For SSH, if not specified, curl
tries the following candidates in order: ‘~/.ssh/id_rsa’,
‘~/.ssh/id_dsa’, ‘./id_rsa’, ‘./id_dsa’.

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

–key-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
(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 support.
This is not very common. Use -V, –version 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 , 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.

You can tell curl to not change the non-GET request method to
GET after a 30x response by using the dedicated options for
that: –post301, –post302 and -post303.

–libcurl
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
Specify the maximum transfer rate you want curl to use – for
both downloads and uploads. This feature is useful if you have a
limited pipe and you’d like your transfer not to use your entire
bandwidth. To make it slower than it otherwise would be.

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] 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
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.

–login-options
Specify the login options to use during server authentication.

You can use the login options to specify protocol specific
options that may be used during authentication. At present only
IMAP, POP3 and SMTP support login options. For more information
about the login options please see RFC 2384, RFC 5092 and IETF
draft draft-earhart-url-smtp-00.txt (Added in 7.34.0).

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

–mail-auth

(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

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

(Added in 7.20.0)

–max-filesize
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

(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
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(5) ftp 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-read‐
able). 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 Negotiate (SPNEGO) authentication.

If you want to enable Negotiate (SPNEGO) for proxy authentica‐
tion, then use –proxy-negotiate.

This option requires a library built with GSS-API or SSPI sup‐
port. Use -V, –version to see if your curl supports GSS-
API/SSPI and SPNEGO.

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
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
Write output to instead of stdout. If you are using {} or
[] to fetch multiple documents, you can use ‘#’ followed by a
number in the 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.

–proxy-header

(HTTP) Extra header to include in the request when sending HTTP
to a proxy. You may specify any number of extra headers. This is
the equivalent option to -H, –header but is for proxy communi‐
cation only like in CONNECT requests when you want a separate
header sent to the proxy to what is sent to the actual remote
host.

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.

Headers specified with this option will not be included in
requests that curl knows will not be sent to a proxy.

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

(Added in 7.37.0)

-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

(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.

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.
Disable 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 specify 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 (SSL/SSH) Passphrase for the private key

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

–path-as-is
Tell curl to not handle sequences of /../ or /./ in the given
URL path. Normally curl will squash or merge them according to
standards but with this option set you tell it not to do that.

(Added in 7.42.0)

–post301
(HTTP) Tells curl to respect RFC 7230/6.4.2 and not convert POST
requests into GET requests when following a 301 redirection. 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 redi‐
rection. This option is meaningful only when using -L, –loca‐
tion (Added in 7.17.1)

–post302
(HTTP) Tells curl to respect RFC 7230/6.4.3 and not convert POST
requests into GET requests when following a 302 redirection. 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 redi‐
rection. This option is meaningful only when using -L, –loca‐
tion (Added in 7.19.1)

–post303
(HTTP) Tells curl to respect RFC 7230/6.4.4 and not convert POST
requests into GET requests when following a 303 redirection. 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 redi‐
rection. This option is meaningful only when using -L, –loca‐
tion (Added in 7.26.0)

–proto 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-default Tells curl to use protocol for any URL missing a scheme name.

Example:

–proto-default https ftp.mozilla.org
https://ftp.mozilla.org

An unknown or unsupported protocol causes error CURLE_UNSUPPORTED_PRO‐
TOCOL.

This option does not change the default proxy protocol (http).

Without this option curl would make a guess based on the host, see
–url for details.

(Added in 7.45.0)

–proto-redir Tells curl to use the listed protocols on redirect. See –proto
for how protocols are represented.

Example:

–proto-redir -all,http,https
Allow only HTTP and HTTPS on redirect.

By default curl will allow all protocols on redirect except several
disabled for security reasons: Since 7.19.4 FILE and SCP are disabled,
and since 7.40.0 SMB and SMBS are also disabled. Specifying all or +all
enables all protocols on redirect, including those disabled for secu‐
rity.

(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 (SPNEGO) authentication when
communicating with the given proxy. Use –negotiate for enabling
HTTP Negotiate (SPNEGO) 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.

–proxy-service-name
This option allows you to change the service name for proxy
negotiation.

Examples: –proxy-negotiate proxy-name –proxy-service-name
sockd would use sockd/proxy-name. (Added in 7.43.0).

–proxy1.0 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
(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.

(As of 7.39.0, curl attempts to automatically extract the public
key from the private key file, so passing this option is gener‐
ally not required. Note that this public key extraction requires
libcurl to be linked against a copy of libssh2 1.2.8 or higher
that is itself linked against OpenSSL.)

-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
(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
(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(*)(HTTP)

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

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

Only digit characters (0-9) are valid in the ‘start’ and ‘stop’
fields of the ‘start-stop’ range syntax. If a non-digit charac‐
ter is given in the range, the server’s response will be unspec‐
ified, 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’ syntax (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
(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
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
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
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
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)

–service-name
This option allows you to change the service name for SPNEGO.

Examples: –negotiate –service-name sockd would use
sockd/server-name. (Added in 7.43.0).

-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 workarounds 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)

–ssl-no-revoke
(WinSSL) This option tells curl to disable certificate revoca‐
tion checks. WARNING: this option loosens the SSL security, and
by using this flag you ask for exactly that. (Added in 7.44.0)

–socks4
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
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
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
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
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 GSS-API 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
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
Pass options to the telnet protocol. Supported options are:

TTYPE= Sets the terminal type.

XDISPLOC= Sets the X display location.

NEW_ENV= Sets an environment variable.

-T, –upload-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
(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
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 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
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
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
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)

–unix-socket (HTTP) Connect through this Unix domain socket, instead of using
the network. (Added in 7.40.0)

-u, –user
Specify the user name and password to use for server authentica‐
tion. Overrides -n, –netrc and –netrc-optional.

If you simply specify the user name, curl will prompt for a
password.

The user name and passwords are split up on the first colon,
which makes it impossible to use a colon in the user name with
this option. The password can, still.

When using Kerberos V5 with a Windows based server you should
include the Windows domain name in the user name, in order for
the server to successfully obtain a Kerberos Ticket. If you
don’t then the initial authentication handshake may fail.

When using NTLM, the user name can be specified simply as the
user name, without the domain, if there is a single domain and
forest in your setup for example.

To specify the domain name use either Down-Level Logon Name or
UPN (User Principal Name) formats. For example, EXAMPLE\user and
user@example.com respectively.

If you use a Windows SSPI-enabled curl binary and perform Ker‐
beros V5, Negotiate, NTLM or Digest authentication then you can
tell curl to select the user name and password from your envi‐
ronment by specifying a single colon with this option: “-u :”.

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

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

If you use a Windows SSPI-enabled curl binary and do either
Negotiate or NTLM authentication then you can tell curl to
select the user name and password from your environment by spec‐
ifying a single colon with this option: “-U :”.

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

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

If the given URL is missing a scheme name (such as “http://” or
“ftp://” etc) then curl will make a guess based on the host. If
the outermost sub-domain name matches DICT, FTP, IMAP, LDAP,
POP3 or SMTP then that protocol will be used, otherwise HTTP
will be used. Since 7.45.0 guessing can be disabled by setting a
default protocol, see –proto-default for details.

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
Be more verbose/talkative during the operation. Useful for
debugging and seeing what’s going on “under the hood”. 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 Make curl display information on stdout after a completed trans‐
fer. The format is a string that may contain plain text mixed
with any number of variables. The format can be specified as a
literal “string”, or you can have curl read the format from a
file with “@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
(HTTP) Specifies a custom request method to use when communicat‐
ing with the HTTP server. The specified request method will be
used instead of the method otherwise used (which defaults to
GET). Read the HTTP 1.1 specification for details and explana‐
tions. 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.

The method string you set with -X will be used for all requests,
which if you for example use -L, –location may cause unintended
side-effects when curl doesn’t change request method according
to the HTTP 30x response codes – and similar.

(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 instead 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

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
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 |
(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 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
instead. See the curl_getdate 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. This lists all current command line options with a
short description.

-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 SSL versions of various protocols are supported, such as
HTTPS, FTPS, POP3S and so on.

libz Automatic decompression of compressed files over HTTP is
supported.

NTLM NTLM authentication 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. Asynchronous
name resolves can be done using either the c-ares or the
threaded resolver backends.

SPNEGO SPNEGO authentication is supported.

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

IDN This curl supports IDN – international domain names.

GSS-API
GSS-API is supported.

SSPI SSPI is supported.

TLS-SRP
SRP (Secure Remote Password) authentication is supported
for TLS.

HTTP2 HTTP/2 support has been built-in.

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://][:port] Sets the proxy server to use for HTTP.

HTTPS_PROXY [protocol://][:port] Sets the proxy server to use for HTTPS.

[url-protocol]_PROXY [protocol://][: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://][:port] Sets the proxy server to use if no protocol-specific proxy is
set.

NO_PROXY
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

90 SSL public key does not matched pinned public key

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, wget

Curl 7.40.0 30 Nov 2014 curl