NAME

curl - transfer a URL


SYNOPSIS

 curl [options] [URL...]


DESCRIPTION

FOREWORD

curl is a tool to transfer data from or to a server, using one of the supported protocols (HTTP, HTTPS, FTP, FTPS, TFTP, DICT, TELNET, LDAP or FILE). The command is designed to work without user interaction.

curl offers a busload of useful tricks like proxy support, user authentication, ftp upload, HTTP post, SSL (https:) connections, cookies, file transfer resume and more. As you will see below, the amount of features will make your head spin!

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

The URL syntax is protocol dependent. You'll find a detailed description 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

No nesting of the sequences is supported at the moment, 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.

Since curl 7.15.1 you can also specify step counter for the ranges, so that you can get every Nth number or letter:

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

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

Curl will attempt to re-use connections for multiple file transfers, so that getting many files from the same server will not do multiple connects / 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 amount of transfered data, transfer speeds and estimated time left etc.

However, since curl displays data to the terminal by default, 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 is not spitting out any response data to the terminal.

If you prefer a progress bar instead of the regular meter, option -# is your friend.


OPTIONS

-0/--http1.0

(HTTP) Forces curl to issue its requests using HTTP 1.0 instead of using its internally preferred: HTTP 1.1.

-1/--tlsv1

(HTTPS) Forces curl to use TSL version 1 when negotiating with a remote TLS server.

-2/--sslv2

(HTTPS) Forces curl to use SSL version 2 when negotiating with a remote SSL server.

-3/--sslv3

(HTTPS) Forces curl to use SSL version 3 when negotiating with a remote SSL server.

--3p-quote

(FTP) Specify arbitrary commands to send to the source server. See the -Q/--quote option for details. (Added in 7.13.0)

--3p-url

(FTP) Activates a FTP 3rd party transfer. Specifies the source URL to get a file from, while the "normal" URL will be used as target URL, the file that will be written/created.

Note that not all FTP server allow 3rd party transfers. (Added in 7.13.0)

--3p-user

(FTP) Specify user:password for the source URL transfer. (Added in 7.13.0)

-4/--ipv4

If libcurl is capable of resolving an address to multiple IP versions (which it is if it is ipv6-capable), this option tells libcurl to resolve names to IPv4 addresses only.

-6/--ipv6

If libcurl is capable of resolving an address to multiple IP versions (which it is if it is ipv6-capable), this option tells libcurl to resolve names to IPv6 addresses only.

-#/--progress-bar

Make curl display progress information as a progress bar instead of the default statistics.

If this option is used twice, the second will again disable the progress bar.

-a/--append

(FTP) When used in an FTP upload, this will tell curl to append to the target file instead of overwriting it. If the file doesn't exist, it will be created.

If this option is used twice, the second one will disable append mode again.

-A/--user-agent "agent string"

(HTTP) Specify the User-Agent: string to send to the HTTP server. Some badly done CGIs fail if its not 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 set more than once, the last one will be the one that's used.

--anyauth

(HTTP) Tells curl to figure out authentication method by itself, and use the most secure one the remote site claims it supports. This is done by first doing a request and checking the response headers, thus inducing an extra network roundtrip. 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.

If this option is used several times, the following occurrences make no difference.

-b/--cookie name=data

(HTTP) Pass the data to the HTTP server as a cookie. It is supposedly 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 '=' letter is used in the line, it is treated as a filename to use to read previously stored cookie lines from, which should be used in this session if they match. Using this method also activates the "cookie parser" which will make curl record incoming cookies too, which may be handy if you're using this in combination with the -L/--location option. The file format of the file to read cookies from should be plain HTTP headers or the Netscape/Mozilla cookie file format.

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

If this option is set more than once, the last one will be the one that's used.

-B/--use-ascii

Enable ASCII transfer when using FTP or LDAP. 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.

If this option is used twice, the second one will disable ASCII usage.

--basic

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

If this option is used several times, the following occurrences make no difference.

--ciphers <list of ciphers>

(SSL) Specifies which ciphers to use in the connection. The list of ciphers must be using valid ciphers. Read up on SSL cipher list details at http://www.openssl.org/docs/apps/ciphers.html.

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

--compressed

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

If this option is used several times, each occurrence will toggle it on/off.

--connect-timeout seconds

Maximum time in seconds that you allow the connection to the server to take. This only limits the connection phase, once curl has connected this option is of no more use. See also the -m/--max-time option.

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

-c/--cookie-jar file

Specify to which file you want curl to write all cookies after a completed operation. Curl writes all cookies previously read from a specified file as well as all cookies received from remote server(s). If no cookies are known, no file will be written. 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.

NOTE 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 feedback you get about this possibly lethal situation.

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

-C/--continue-at offset

Continue/Resume a previous file transfer at the given offset. The given offset is the exact number of bytes that will be skipped counted 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.

--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, try --ftp-create-dirs.

--crlf

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

If this option is used several times, the following occurrences make no difference.

-d/--data data

(HTTP) Sends the specified data in a POST request to the HTTP server, in a way that can emulate as if a user has filled in a HTML form and pressed the submit button. Note that the data is sent exactly as specified with no extra processing (with all newlines cut off). The data is expected to be "url-encoded". This will cause curl to pass the data to the server using the Content-type: header with value application/x-www-form-urlencoded. Compare to -F/--form. If this option is used more than once on the same command line, the data pieces specified will be merged together with a separating &-letter. 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. The contents of the file must already be url-encoded. Multiple files can also be specified. Posting data from a file named 'foobar' would thus be done with --data @foobar.

To post data purely binary, you should instead use the --data-binary option.

If this option is used several times, the ones following the first will append data.

--data-ascii data

(HTTP) This is an alias for the -d/--data option.

If this option is used several times, the ones following the first will append data.

--data-binary data

(HTTP) This posts data in a similar manner as --data-ascii does, although when using this option the entire context of the posted data is kept as-is. If you want to post a binary file without the strip-newlines feature of the --data-ascii option, this is for you.

If this option is used several times, the ones following the first will append data.

--digest

(HTTP) Enables HTTP Digest authentication. This is a authentication 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, the following occurrences make no difference.

--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 extensions to the original FTP protocol, may not work on all servers but enable more functionality in a better way than the traditional PORT command.

If this option is used several times, each occurrence will toggle this on/off.

--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.

If this option is used several times, each occurrence will toggle this on/off.

-D/--dump-header file

Write the protocol headers to the specified file.

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

When used on 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.

-e/--referer URL

(HTTP) Sends the "Referer Page" information to the HTTP server. This can also be set with the -H/--header flag of course. When used with -L/--location you can append ";auto" to the --referer URL to make curl automatically set the previous URL when it follows 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.

--engine name

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

--environment

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

If this option is used several times, each occurrence will toggle this on/off.

--egd-file file

(HTTPS) 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.

-E/--cert certificate[:password]

(HTTPS) Tells curl to use the specified certificate file when getting a file with HTTPS. The certificate must be in PEM format. If the optional password isn't specified, it will be queried for on the terminal. Note that this certificate is the private key and the private certificate concatenated!

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

--cert-type type

(SSL) Tells curl what certificate type the provided certificate is in. PEM, DER and ENG are recognized types.

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

--cacert CA-certificate

(HTTPS) 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.

curl recognizes the environment variable named 'CURL_CA_BUNDLE' if that 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 directory as curl.exe, or in the Current Working Directory, or in any folder along your PATH.

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

--capath <CA certificate directory>

(HTTPS) Tells curl to use the specified certificate directory to verify the peer. The certificates must be in PEM format, and the directory must have been processed using the c_rehash utility supplied with openssl. Using --capath can allow curl to make https connections much more efficiently than using --cacert if the --cacert file contains many CA certificates.

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

-f/--fail

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

If this option is used twice, the second will again disable silent failure.

--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 twice, the second will override the previous use.

--ftp-create-dirs

(FTP) When an FTP 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.

If this option is used twice, the second will again disable directory creation.

--ftp-method [method]

(FTP) Control what method curl should use to reach a file on a FTP(S) server. The method argument should be one of the following 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 RFC1738 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 commands. 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 'multicwd'.

--ftp-pasv

(FTP) Use PASV when transferring. PASV is the internal default behavior, but using this option can be used to override a previous --ftp-port option. (Added in 7.11.0)

If this option is used several times, the following occurrences make no difference.

--ftp-alternative-to-user command

(FTP) If authenticating with the USER and PASS commands fails, send this command. When connecting to Tumbleweed's Secure Transport server over FTPS using a client certificate, using "SITE AUTH" will tell the server to retrieve the username from the certificate. (Added in 7.15.5)

--ftp-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 reuse 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.

If this option is used twice, the second will again use the server's suggested address.

--ftp-ssl

(FTP) Try to use SSL/TLS for the FTP connection. Reverts to a non-secure connection if the server doesn't support SSL/TLS. (Added in 7.11.0)

If this option is used twice, the second will again disable this.

--ftp-ssl-reqd

(FTP) Require SSL/TLS for the FTP connection. Terminates the connection if the server doesn't support SSL/TLS. (Added in 7.15.5)

If this option is used twice, the second will again disable this.

-F/--form name=content

(HTTP) This lets curl emulate a filled in form in which a user has pressed the submit button. This causes curl to POST data using the Content-Type multipart form data according to RFC1867. 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 letter <. 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 'password' 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 the file's content from stdin instead of a file, use - where the file name should've been. This goes for both @ and < constructs.

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

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

or

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

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

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

See further examples and details in the MANUAL. This option can be used multiple times.

--form-string name=string

(HTTP) Similar to --form except that the value string for the named parameter is used literally. Leading '@' and '<' characters, and the ;type= string in the value have no special meaning. Use this in preference to --form if there's any possibility that the string value may accidentally trigger the '@' or '<' features of --form.

-g/--globoffa

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 or --data-binary to be used in a 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, the following occurrences make no difference.

-h/--help

Usage help.

-H/--header header

(HTTP) Extra header to use when getting a web page. You may specify any number of extra headers. Note that if you should add a custom header that has the same name as one of the internal ones curl would use, your externally set header will be used instead of the internal one. This allows you to make even trickier stuff than curl would normally do. You should not replace internally set headers without knowing perfectly well what you're doing. Replacing an internal header with one without content on the right side of the colon will prevent that header from appearing.

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

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

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

--ignore-content-length

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

-i/--include

(HTTP) Include the HTTP-header in the output. The HTTP-header includes things like Server-name:, Date: of the document, HTTP-version: and more.

If this option is used twice, the second will again disable header include.

--interface iface

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.

-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 a FTP or FILE file, curl displays the file size and last modification time only.

If this option is used twice, the second will again disable header only.

-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.

If this option is used several times, each occurrence will toggle this on/off.

-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" to fail unless -k/--insecure is used.

If this option is used twice, the second time will again disable it.

--key key

(SSL) Private key file name. Allows you to provide your private key in this separate file.

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

--key-type type

(SSL) Private key file type. Specify which type your --key provided private key is. DER, PEM and ENG are supported.

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

--krb4 level

(FTP) Enable kerberos4 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 that the library was 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.

-K/--config file

Specify which config file to read curl arguments from. The config 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 config file line. If the parameter is to contain white spaces, the parameter must be enclosed within quotes. If the first column of a config line is a '#' character, the rest of the line will be treated as a comment.

Specify the filename 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/"

This option can be used multiple times.

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:

--limit-rate speed

Specify the maximum transfer rate you want curl to use. This feature is useful if you have a limited pipe and you'd like your transfer not use your entire bandwidth.

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

If you are also using the -Y/--speed-limit option, that option will take precedence and might cripple the ratelimiting slightly, to help keeping the speed limit logic working.

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. Especially useful if you want to machine parse the contents of an FTP directory since the normal directory view doesn't use a standard look or format.

This option causes an FTP NLST command to be sent. Some FTP servers list only files in their response to NLST; they do not include subdirectories and symbolic links.

If this option is used twice, the second will again disable list only.

--local-port num[-num]

Set a prefered number or range of local port numbers to use for the connection(s). Note that port numbers by nature is 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)

-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 --location-trusted on how to change this. You can limit the amount of redirects to follow by using the --max-redirs option.

If this option is used twice, the second will again disable location following.

--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 do a site to which you'll send your authentication info (which is plaintext in the case of HTTP Basic authentication).

If this option is used twice, the second will again disable location following.

--max-filesize bytes

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

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

-m/--max-time seconds

Maximum time in seconds that you allow the whole operation to take. This is useful for preventing your batch jobs from hanging for hours due to slow networks or links going down. See also the --connect-timeout option.

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

-M/--manual

Manual. Display the huge help text.

--max-redirs num

Set maximum number of redirection followings allowed. If -L/--location is used, this option can be used to prevent curl from following redirections "in absurdum". By default, the limit is set to 50 redirections. Set this option to -1 to make it limitless.

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

-n/--netrc

Makes curl scan the .netrc file in the user's home directory for login name and password. This is typically used for ftp on unix. If used with http, curl will enable user authentication. See netrc(4) or ftp(1) for details on the file format. Curl will not complain if that file hasn't the right permissions (it should not be world nor group readable). The environment variable HOME is used to find the home directory.

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

    machine host.domain.com login myself password secret

If this option is used twice, the second will again disable netrc usage.

--netrc-optional

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

--negotiate

(HTTP) Enables GSS-Negotiate authentication. The GSS-Negotiate method was designed by Microsoft and is used in their web applications. It is primarily meant as a support for Kerberos5 authentication but may be also used along with another authentication methods. For more information see IETF draft HTTP Authentication: SPNEGO Access Authentication As implemented in Microsoft Windows 2000 2002 by J. Brezak; http://www.ietf.org/internet-drafts/draft-brezak-spnego-http-04.txt

This option requires that the library was built with GSSAPI support. This is not very common. Use -V/--version to see if your version supports GSS-Negotiate.

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

If this option is used several times, the following occurrences make no difference.

-N/--no-buffer

Disables the buffering of the output stream. In normal work situations, 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.

If this option is used twice, the second will again switch on buffering.

--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, reversed engineered by clever people 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 authentication method instead. Such as Digest.

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

This option requires that the library was built with SSL support. Use -V/--version to see if your curl supports NTLM.

If this option is used several times, the following occurrences make no difference.

-o/--output file

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

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

or use several variables like:

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

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

See also the --create-dirs option to create the local directories dynamically.

-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.

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

--pass phrase

(SSL) Pass phrase for the private key

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

--proxy-anyauth

Tells curl to pick a suitable authentication method when communicating with the given proxy. This will cause an extra request/response roundtrip. (Added in 7.13.2)

If this option is used twice, the second will again disable the proxy use-any authentication.

--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.

If this option is used twice, the second will again disable proxy HTTP Basic authentication.

--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.

If this option is used twice, the second will again disable proxy HTTP Digest.

--proxy-ntlm

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

If this option is used twice, the second will again disable proxy HTTP NTLM.

-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 tunnel 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.

If this option is used twice, the second will again disable proxy tunnel.

-P/--ftp-port address

(FTP) Reverses the initiator/listener roles when connecting with ftp. This switch makes Curl use the PORT command instead of PASV. In practice, PORT tells the server to connect to the client's specified address and port, while PASV asks the server for an ip address and port to connect to. Value of address should be one of:

interface

i.e "eth0" to specify which interface's IP address you want to use (Unix only)

IP address

i.e "192.168.10.1" to specify exact IP number

host name

i.e "my.host.domain" to specify 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++.

-q

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

-Q/--quote command

(FTP) Send an arbitrary command to the remote FTP server. Quote commands are sent BEFORE the transfer is taking place (just after the initial PWD command to be exact). To make commands take place after a successful transfer, prefix them with a dash '-'. To make commands get sent after libcurl has changed working directory, just before the transfer command(s), prefix the command with '+'. You may specify any amount of commands. If the server returns failure for one of the commands, the entire operation will be aborted. You must send syntactically correct FTP commands as RFC959 defines.

This option can be used multiple times.

--random-file file

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

-r/--range range

(HTTP/FTP) Retrieve a byte range (i.e a partial document) from a HTTP/1.1 or FTP server. Ranges can be specified in a number of ways.

value 0-499

specifies the first 500 bytes

value 500-999

specifies the second 500 bytes

value-500

specifies the last 500 bytes

value 9500-

specifies the bytes from offset 9500 and forward

value 0-0,-1

specifies the first and last byte only(*)(H)

value 500-700,600-799

specifies 300 bytes from offset 500(H)

value 100-199,500-599

specifies two separate 100 bytes ranges(*)(H)

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

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 range downloads only support the simple syntax 'start-stop' (optionally with one of the numbers omitted). It depends on the non-RFC command SIZE.

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

-R/--remote-time

When used, this will make libcurl attempt to figure out the timestamp of the remote file, and if that is available make the local file get that same timestamp.

If this option is used twice, the second time disables this again.

--retry num

If a transient error is returned when curl tries to perform a transfer, it will retry this number of times before giving up. Setting the number to 0 makes curl do no retries (which is the default). Transient error means either: a timeout, an FTP 5xx 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 multiple times, the last occurrence decide the amount.

--retry-delay seconds

Make curl sleep this amount of time between 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 multiple times, the last occurrence decide the amount.

--retry-max-time seconds

The retry timer is reset before the first transfer attempt. Retries will be done as usual (see --retry) as long as the timer hasn't reached this given limit. Notice that if the timer hasn't reached the limit, the request will be made and while performing, 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 multiple times, the last occurrence decide the amount.

-s/--silent

Silent mode. Don't show progress meter or error messages. Makes Curl mute.

If this option is used twice, the second will again disable silent mode.

-S/--show-error

When used with -s it makes curl show error message if it fails.

If this option is used twice, the second will again disable show error.

--socks4 host[:port]

Use the specified SOCKS4 proxy. If the port number is not specified, 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.

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

--socks5 host[:port]

Use the specified SOCKS5 proxy. If the port number is not specified, it is assumed at port 1080. (Added in 7.11.1)

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

If this option is used several times, the last one will be used. (This option was previously wrongly documented and used as --socks4 without the number appended.)

--stderr file

Redirect all writes to stderr to the specified file instead. If the file name is a plain '-', it is instead written to stdout. This option has no point when you're using a shell with decent redirecting capabilities.

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

--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)

If this option is used several times, each occurrence toggles this on/off.

-t/--telnet-option OPT=val

Pass options to the telnet protocol. Supported options are:

    TTYPE=<term>            Sets the terminal type.
    XDISPLOC=<X display>    Sets the X display location.
    NEW_ENV=<var,val>       Sets an environment variable.
-T/--upload-file file

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

Use the file name "-" (a single dash) to use stdin instead of a given file.

You can specify one -T for each URL on the command line. Each -T URL option specifies what to upload and to where. curl also supports "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/
--trace file

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

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

--trace-ascii file

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

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

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)

If this option is used several times, each occurrence will toggle it on/off.

-u/--user user:password

Specify user and password to use for server authentication. Overrides -n/--netrc and --netrc-optional.

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

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

-U/--proxy-user user:password

Specify user and password to use for proxy authentication.

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

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

--url URL

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

This option may be used any number of times. To control where this URL is written, use the -o/--output or the -O/--remote-name options.

-v/--verbose

Makes the fetching more verbose/talkative. Mostly usable for debugging. Lines starting with > means "header data" sent by curl, < means "header data" received by curl that is hidden in normal cases and lines starting with * means additional info provided by curl.

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

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

If this option is used twice, the second will again disable verbose.

-V/--version

Displays information about curl and the libcurl version it uses.

The first line includes the full version of curl, libcurl and other 3rd party libraries linked with the executable.

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

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

IPv6

You can use IPv6 with this.

krb4

Krb4 for ftp is supported.

SSL

HTTPS and FTPS are supported.

libz

Automatic decompression of compressed files over HTTP is supported.

NTLM

NTLM authentication is supported.

GSS-Negotiate

Negotiate authentication is supported.

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

AsynchDNS

This curl uses asynchronous name resolves.

SPNEGO

SPNEGO Negotiate authentication is supported.

Largefile

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

IDN

This curl supports IDN - international domain names.

SSPI

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

-w/--write-out format

Defines what to display on stdout after a completed and successful operation. The format is a string that may contain plain text mixed with any number of variables. The string can be specified as "string", to get read from a particular file you specify it @filename and to tell curl to read the format from stdin you write @-.

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

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

Available variables are at this point:

url_effective

The URL that was fetched last. This is mostly meaningful if you've told curl to follow Location: headers.

http_code

The numerical code that was found in the last retrieved HTTP(S) page.

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)

time_total

The total time, in seconds, that the full operation lasted. The time will be displayed with millisecond resolution.

time_namelookup

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

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

time_pretransfer

The time, in seconds, it took from the start until the file transfer is just about to begin. This includes all pretransfer commands and negotiations that are specific to the particular protocol(s) involved.

time_redirect

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

time_starttransfer

The time, in seconds, it took from the start until the first byte is just about to be transferred. This includes time_pretransfer and also the time the server needs to calculate the result.

size_download

The total amount of bytes that were downloaded.

size_upload

The total amount of bytes that were uploaded.

size_header

The total amount of bytes of the downloaded headers.

size_request

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

speed_download

The average download speed that curl measured for the complete download.

speed_upload

The average upload speed that curl measured for the complete upload.

content_type

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

num_connects

Number of new connects made in the recent transfer. (Added in 7.12.3)

num_redirects

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

ftp_entry_path

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

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

-x/--proxy proxyhost[:port]

Use specified HTTP proxy. If the port number is not specified, it is assumed at port 1080.

This option overrides existing environment variables that sets proxy to use. If there's an environment variable setting a proxy, you can set proxy to "" to override it.

Note that all operations that are performed over a HTTP proxy will transparently 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 done with the -p/--proxytunnel option.

Starting with 7.14.1, the proxy host can be specified the exact same way as the proxy environment variables, include protocol prefix (http://) and embedded user + password.

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

-X/--request command

(HTTP) Specifies a custom request method to use when communicating with the HTTP server. The specified request will be used instead of the method otherwise used (which defaults to GET). Read the HTTP 1.1 specification for details and explanations.

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

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

-y/--speed-time time

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

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

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

-Y/--speed-limit speed

If a download is slower than this given speed, in bytes per second, for speed-time seconds it gets aborted. speed-time is set with -Y and is 30 if not set.

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

-z/--time-cond date

(HTTP) Request a file that has been modified later than the given time and date, or one that has been modified before that time. The date expression can be all sorts of date strings or if it doesn't match any internal ones, it tries to get the time from a given file name instead! See the curl_getdate(3) man pages for date expression details.

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

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


EXAMPLES

For more complete documentation refer to http://curl.haxx.se/docs/

DOWNLOAD METHODS

Downloading To Stdout

Get the main page:

    curl http://www.google.com/

Get a directory listing with port number:

    curl ftp://www.haxx.se:2121/

Fetch two documents at once:

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

Get the definition of curl from a dictionary:

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

Get a file off an FTPS server:

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

A better way to get file from FTPS:

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

Some sites do not allow robots, so pretend to be a browser by changing User-Agent:. In addition pretent the requets to come from another source by changing Refferer:

    curl -A 'Mozilla/5.0' -e www.cool.com ftp://www.haxx.se/

To see if the page is there, retrieve only first 100 bytes:

    curl -r 0-99 http://www.example.com/

Downloading Using Passwords

Basic use:

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

And through proxy:

    http_proxy=http://proxy:port
    curl http://name:passwd@machine.domain:port/full/path/to/file

Some proxies require special authentication. Here is example pecifying proxy with -x option

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

The FTPS is just like FTP, but you may also want to specify and use SSL-specific options for certificates etc. Note that using ftps:// as prefix is the "implicit" way as described in the standards while the recommended "explicit" way is done by using ftp:// and the --ftp-ssl option.

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

When using Curl via a proxy, you may need to use -u if you need to send passwords.

Download To a File

Get a web page and store in a local file:

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

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

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

Fetch two files and store them with their remote names:

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

Ftp and Path Names

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

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

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

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

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

DOWNLOAD TIPS

Resuming File Transfers

To continue a file transfer where it was previously aborted, curl supports resume on http(s) downloads as well as ftp uploads and downloads.

Continue downloading a document:

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

Continue uploading a document(*1):

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

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

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

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

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

Time Conditions

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

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

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

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

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

You can specify a "free text" date as condition. Tell curl to only download the file if it was updated since yesterday:

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

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

Downloading Through Proxies

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

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

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

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

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

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

Curl also supports SOCKS4 and SOCKS5 proxies with --socks4 and --socks5. See also the environment variables Curl support that offer further proxy control.

Download Bytes (Ranges)

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

Get the first 100 bytes of a document:

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

Get the last 500 bytes of a document:

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

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

Get the first 100 bytes of a document using FTP:

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

UPLOADING FILES

Upload all data on stdin to a specified ftp site:

    curl -T - ftp://ftp.example.com/myfile

Upload file.txt with login and password:

    curl -T file.txt ftp://login:pass@ftp.example.com/myfile

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

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

Upload using HTTP PUT:

    curl -T file.txt http://www.example.com/

In case the upload must go through HTTP proxy, add option --proxytunnel. This only works for HTTP proxys. Curl does not support pure FTP proxys.

    curl -p -x proxy:port -T file.txt ftp.exmaple.com

POSTING DATA TO WEB PAGES (HTTP POST)

It's easy to post data using curl. This is done using the -d option. Post a simple "name" and "phone" fields to guestbook. The post data must have been urlencoded by you:

    curl -d "name=foo&phone=3320780" http://www.example.com/guest.cgi

While -d uses the application/x-www-form-urlencoded mime-type, generally understood by CGI's and similar, curl also supports the more capable multipart/form-data type. This latter type supports things like file upload.

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

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

If the Content-type: is not specified, curl will try to guess from the file extension (it only knows a few), or use the previously specified type (from an earlier file if several files are specified in a list) or else it will using the default type text/plain.

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

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

Suppose the HTML form is in site that requires registration information before download link appears. In that case, add option -L/--location to make curl follow the announced 'Location:' header in the HTTP response. If it's a binary file, then you need to redirect the output to file.

    curl -F "first_name=Foo" \
         -F "last_name=Bar" \
         -L \
         -o package.tar.gz \
         http://www.example.com/postit.cgi

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

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

    curl -F "pictures=@dog.gif,cat.gif"

2. Send two fields with two field names: curl -F "docpicture=@dog.gif" -F "catpicture=@cat.gif"

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

Lesson: How to post a form with curl

Dig out all the HTML form's input tags that you want to fill in. (There's a perl program called formfind.pl on the curl site that helps with this). If there's a "normal" post, you use -d to post. This option takes a full "post string", which is in the format

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

The 'variable' names are the names set with "name=" in the <input> tags, and the data is the contents you want to fill in for the inputs. The data *must* be properly URL encoded. That means you replace space with + and that you write weird letters with %XX where XX is the hexadecimal representation of the letter's ASCII code. An Example from http://www.formpost.com/getthis/

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

CONTROLLING HTTP

Referrer Header

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

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

NOTE: The referer field is defined in the HTTP spec to be a full URL.

User-Agent Header

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

Example:

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

Other common strings:

    'Mozilla/4.05 [en] (X11; U; Linux 2.0.32 i586)'      NS for Linux

Note that Internet Explorer tries hard to be compatible in every way:

    'Mozilla/4.0 (compatible; MSIE 4.01; Windows 95)'    MSIE for W95

Mozilla is not the only possible User-Agent name:

    'Konqueror/1.0'             KDE File Manager desktop client
    'Lynx/2.7.1 libwww-FM/2.14' Lynx command line browser

Extra Headers

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

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

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

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

    curl -H "Host:" www.server.com

Cookies

The cookie response header looks like this:

    Set-Cookie: sessionid=boo123; path="/foo";

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

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

    curl -b "name=Daniel" www.example.com

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

    curl --dump-header headers www.example.com

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

    curl -b headers www.example.com

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

    curl -c cookies.txt www.example.com

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

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

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

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

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

NETWORKING

Ftp and Firewalls

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

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

      curl ftp.download.com

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

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

      curl -P - ftp.download.com

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

      curl -P le0 ftp.download.com

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

      curl -P 192.168.0.10 ftp.download.com

Selecting Network Interface

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

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

or

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

Ldap

If you have installed the OpenLDAP library, curl can take advantage of it and offer ldap:// support. LDAP is a complex thing and writing an LDAP query is not an easy task. I do advice you to dig up the syntax description for that elsewhere. Two places that might suit you are:

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

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

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

Kerberos4 Ftp Transfer

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

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

    curl --krb4 private ftp://krb4site.com -u username:fakepwd

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

Telnet

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

    curl telnet://remote.server.com

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

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

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

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

Other interesting options for it -t include:

    - XDISPLOC=<X display> Sets the X display location.
    - NEW_ENV=<var,val> Sets an environment variable.

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

CONNECTIONS

Persistent Connections

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

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

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

Multiple Transfers With a Single Command Line

As is mentioned above, you can download multiple files with one command line by simply adding more URLs. If you want those to get saved to a local file instead of just printed to stdout, you need to add one save option for each URL you specify. Note that this also goes for the -O option.

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

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

You can also upload multiple files in a similar fashion:

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

Progress Meter

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

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

From left-to-right:

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

Limiting Transfer Speed

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

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

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

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

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

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

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

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

or

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

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

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

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

CUSTOM OUTPUT

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

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

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

CONFIG FILE

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

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

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

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

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

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

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

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

    curl -q www.thatsite.com

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

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

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

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


DEBUGGING

Different protocols provide different ways of getting detailed information about specific files/documents. To get curl to show detailed information use option -I/--head option.

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

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

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

    curl --trace trace.txt www.haxx.se

DETAILED INFORMATION

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

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

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

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

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


FILES

~/.curlrc

Default config file, see -K/--config for details.

~/.netrc

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

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

A very simple .netrc file could look something like:

    machine curl.haxx.se login iamdaniel password mysecret


ENVIRONMENT

http_proxy [protocol://]<host>[:port]

Sets proxy server to use for HTTP.

HTTPS_PROXY [protocol://]<host>[:port]

Sets proxy server to use for HTTPS.

FTP_PROXY [protocol://]<host>[:port]

Sets proxy server to use for FTP.

ALL_PROXY [protocol://]<host>[:port]

Sets proxy server to use if no protocol specific proxy is set.

NO_PROXY <comma separated list of hosts>

list of host names that shouldn't go through any proxy. If set to a asterisk '*' only, it matches all hosts.

SUMMARY: Curl reads and understands the following environment variables:

    http_proxy, HTTPS_PROXY, FTP_PROXY

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

    ALL_PROXY

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

    NO_PROXY

If a tail substring of the domain-path for a host matches one of these strings, transactions with that node will not be proxied.

The usage of the -x/--proxy option overrides the environment variables.


EXIT CODES

There exists a bunch of different error codes and their corresponding error messages that may appear during bad conditions. There will appear more error codes here in future releases. The existing ones are meant to never change. 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 malformat. The syntax was not correct.

  4. URL user malformatted. The user-part of the URL syntax was not correct.

  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.

  10. FTP user/password incorrect. Either one or both were not accepted by the server.

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

  12. FTP weird USER reply. Curl couldn't parse the reply sent to the USER 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.

  16. FTP can't reconnect. Couldn't connect to the host 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 similar) command failed.

  20. FTP write error. The transfer was reported bad by the server.

  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.

  24. Malformed user. User name badly specified.

  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.

  29. FTP couldn't set ASCII. The server returned an unknown reply.

  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.

  32. FTP couldn't use SIZE. The SIZE command failed. The command is an extension to the original FTP spec RFC 959.

  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.

  40. Library not found. The LDAP library was not found.

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

  42. Aborted by callback. An application told curl to abort the operation.

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

  44. Internal error. A function was called in a bad order.

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

  46. Bad password entered. An error was signaled when the password was entered.

  47. Too many redirects. When following redirects, curl hit the maximum amount.

  48. Unknown TELNET option specified.

  49. Malformed telnet option.

  50. The remote peer's SSL certificate wasn't ok

  51. The server didn't reply anything, which here is considered an error.

  52. SSL crypto engine not found

  53. Cannot set SSL crypto engine as default

  54. Failed sending network data

  55. Failure in receiving network data

  56. Share is in use (internal error)

  57. Problem with the local certificate

  58. Couldn't use specified SSL cipher

  59. Problem with the CA cert (path? permission?)

  60. Unrecognized transfer encoding

  61. Invalid LDAP URL

  62. Maximum file size exceeded

  63. Requested FTP SSL level failed

  64. Sending the data requires a rewind that failed

  65. Failed to initialise SSL Engine

  66. User, password or similar was not accepted and curl failed to login

  67. File not found on TFTP server

  68. Permission problem on TFTP server

  69. Out of disk space on TFTP server

  70. Illegal TFTP operation

  71. Unknown TFTP transfer ID

  72. File already exists (TFTP)

  73. No such user (TFTP)

  74. Character conversion failed

  75. Character conversion functions required


SEE ALSO

ftp(1) wget(1)


AUTHORS

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

Curl homepage is at http://curl.haxx.se and the FTP access link is ftp://ftp.sunet.se/pub/www/utilities/curl/