curl - Unix, Linux Command


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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 (HTTP, HTTPS, FTP, FTPS, SCP, SFTP, 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 connections, cookies, file transfer resume and more.

OPTIONS

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

 

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

 

--ciphers <list of ciphers> (SSL) Specifies which ciphers to use in the connection. The list of ciphers must specify valid ciphers. Read up on SSL cipher list details on this URL: http://www.openssl.org/docs/apps/ciphers.html
--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.
--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.
-c/--cookie-jar <file name> 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.
-C/--continue-at <offset> Continue/Resume a previous file transfer at the given offset. The given offset is the exact number of bytes that will be skipped, counting from the beginning of the source file before it is transferred to the destination. If used with uploads, the FTP server command SIZE will not be used by curl.
--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.
--crlf (FTP) Convert LF to CRLF in upload. Useful for MVS (OS/390). --crlfile <file> (HTTPS/FTPS) Provide a file using PEM format with a Certificate Revocation List that may specify peer certificates that are to be considered revoked. If this option is used several times, the last one
-d/--data <data> (HTTP) Sends the specified data in a POST request to the HTTP server, in the same way that a browser does when a user has filled in an HTML form and presses the submit button. This will cause curl to pass the data to the server using the content-type application/x-www-form-urlencoded. Compare to -F/--form.

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

--data-binary <data> (HTTP) This posts data exactly as specified with no extra processing 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 are preserved and conversions are never done.

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

--data-urlencode <data> (HTTP) This posts data, similar to the other --data options with the exception that this performs URL-encoding. (Added in 7.18.0) To be CGI-compliant, the part should begin with a name followed by a separator and a content specification.

The <data> part can be passed to curl using one of the following syntaxes:

--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.
--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, and may not work on all servers, but they enable more functionality in a better way than the traditional PORT command.
--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.

-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 invocation by using the -b/--cookie option! The -c/--cookie-jar option is however a better way to store cookies.
-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.
--engine <name> Select the OpenSSL crypto engine to use for cipher operations. Use --engine list to print a list of build-time supported engines. Note that not all (or none) of the engines may be available at run-time.
--environment (RISC OS ONLY) Sets a range of environment variables, using the names the -w option supports, to allow easier extraction of useful information after having run curl.
--egd-file <file> (SSL) Specify the path name to the Entropy Gathering Daemon socket. The socket is used to seed the random engine for SSL connections. See also the --random-file option.
-E/--cert <certificate[:password]> (SSL) Tells curl to use the specified certificate file when getting a file with HTTPS or FTPS. 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 option assumes a "certificate" file that is the private key and the private certificate concatenated! See --cert and --key to specify them independently.
--cert-type <type> (SSL) Tells curl what certificate type the provided certificate is in. PEM, DER and ENG are recognized types. If not specified, PEM is assumed
--cacert <CA certificate> (SSL) Tells curl to use the specified certificate file to verify the peer. The file may contain multiple CA certificates. The certificate(s) must be in PEM format. Normally curl is built to use a default file for this, so this option is typically used to alter that default file. curl recognizes the environment variable named 'CURL_CA_BUNDLE' if it is set, and uses the given path as a path to a CA cert bundle. This option overrides that variable.
--capath <CA certificate directory> (SSL) Tells curl to use the specified certificate directory to verify the peer. The certificates must be in PEM format.
-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 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.
--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)
--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 a FTP(S) server. The method argument should be one of the following alternatives
--ftp-pasv (FTP) Use passive mode for the data conection. 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, the following occurrences make no difference. Undoing an enforced passive really isn't doable but you must then instead enforce the correct -P/--ftp-port again.
--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 re-use the same IP address it already uses for the control connection. (Added in 7.14.2)
--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. See also --ftp-ssl-control and --ftp-ssl-reqd for different levels of encryption required. (Added in 7.11.0)
--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 support SSL/TLS. (Added in 7.16.0)
--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)
--ftp-ssl-ccc (FTP) Use CCC (Clear Command Channel) Shuts down the SSL/TLS layer after authenticating. The rest of the control channel communication will be unencrypted. This allows NAT routers to follow 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)
-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 RFC2388. 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.
--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/--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 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
-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. Remove an internal header by giving a replacement without content on the right side of the colon, as in: -H "Host:".
--hostpubmd5 <md5> 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. This option is only for SCP and SFTP transfers. (Added in 7.17.1)
--ignore-content-length (HTTP) Ignore the Content-Length header. This is particularly useful for servers running Apache 1.x, which will report 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...
--interface <name> Perform an operation using a specified interface. You can enter interface name, IP address or host name. An example could look like:
-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.
-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.
-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.
--keepalive-time <seconds> This option sets the time a connection needs to remain idle before sending keepalive probes and the time between individual keepalive probes. It is currently effective on operating systems offering the TCP_KEEPIDLE and TCP_KEEPINTVL socket options (meaning Linux, recent AIX, HP-UX and more). This option has no effect if --no-keepalive is used. (Added in 7.18.0)
--key <key> (SSL/SSH) 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 not specified, PEM is assumed.
--krb <level> (FTP) Enable Kerberos authentication and use. The level must be entered and should be one of 'clear', 'safe', 'confidential', or 'private'. Should you use a level that is not one of these, 'private' will instead be used.
-K/--config <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, separated by whitespace, colon, the equals sign or any combination thereof (however, the preferred separator is the equals sign). 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.
--libcurl <file> Append this option to any ordinary curl command line, and you will get a libcurl-using source code written to the file that does the equivalent of what your command-line operation does!
--limit-rate <speed> Specify the maximum transfer rate you want curl to use. This feature is useful if you have a limited pipe and you'd like your transfer not to use your entire bandwidth.
-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.
--local-port <num>[-num] Set a preferred number or range of local port numbers to use for the connection(s). Note that port numbers by nature are a scarce resource that will be busy at times so setting this range to something too narrow might cause unnecessary connection setup failures. (Added in 7.15.2)
-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.
--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).
--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.
-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.
-M/--manual Manual. Display the huge help text.
-n/--netrc Makes curl scan the .netrc (_netrc on Windows) 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 doesn't have the right permissions (it should not be either world- or group-readable). The environment variable "HOME" is used to find the home directory.
--netrc-optional Very similar to --netrc, but this option makes the .netrc usage optional and not mandatory as the --netrc option does.
--negotiate (HTTP) Enables GSS-Negotiate authentication. The GSS-Negotiate method was designed by Microsoft and is used in their web applications. It is primarily meant as a support for Kerberos5 authentication but may be also used along with another authentication method. For more information see IETF draft draft-brezak-spnego-http-04.txt.
-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.
--no-keepalive Disables the use of keepalive messages on the TCP connection, as by default curl enables them.
--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)
--noproxy <no-proxy-list> Comma-separated list of hosts which do not use a proxy, if one is specified. The only wildcard is a single * character, which matches all hosts, and effectively disables the proxy. Each name in this list is matched as either a domain which contains the hostname, or the hostname itself. For example, local.com would match local.com, local.com:80, and www.local.com, but not www.notlocal.com. (Added in 7.19.4).
--ntlm (HTTP) Enables NTLM authentication. The NTLM authentication method was designed by Microsoft and is used by IIS web servers. It is a proprietary protocol, reverse-engineered by clever 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.
-o/--output <file> Write output to <file> instead of stdout. If you are using {} or [] to fetch multiple documents, you can use '#' followed by a number in the <file> specifier. That variable will be replaced with the current string for the URL being fetched. Like in:
-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.)
--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)
--pass <phrase> Passphrase for the private key If this option is used several times, the last one will be used
--post301 Tells curl to respect RFC 2616/10.3.2 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 redirection. This option is meaningful only when using -L/--location (Added in 7.17.1)
--post302 Tells curl to respect RFC 2616/10.3.2 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 redirection. This option is meaningful only when using -L/--location (Added in 7.19.1)
--proxy-anyauth Tells curl to pick a suitable authentication method when communicating with the given proxy. This might cause an extra request/response round-trip. (Added in 7.13.2)
--proxy-basic Tells curl to use HTTP Basic authentication when communicating with the given proxy.

Use --basic for enabling HTTP Basic with a remote host. Basic is the default authentication method curl uses with proxies.

--proxy-digest Tells curl to use HTTP Digest authentication when communicating with the given proxy. Use --digest for enabling HTTP Digest with a remote host.
--proxy-negotiate Tells curl to use HTTP Negotiate authentication when communicating with the given proxy. Use --negotiate for enabling HTTP Negotiate with a remote host. (Added in 7.17.1)
--proxy-ntlm Tells curl to use HTTP NTLM authentication when communicating with the given proxy. Use --ntlm for enabling NTLM with a remote host.
--proxy1.0 <proxyhost[:port]> Use the specified HTTP 1.0 proxy. If the port number is not specified, it is assumed at port 1080.
-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.
--pubkey <key> (SSH) Public key file name. Allows you to provide your public key in this separate file.

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

-P/--ftp-port <address> (FTP) Reverses the default initiator/listener roles when connecting 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

-q If used as the first parameter on the command line, the curlrc config file will not be read and used. See the -K/--config for details on the default config file search path.
-Q/--quote <command> (FTP/SFTP) Send an arbitrary command to the remote FTP or SFTP server. Quote commands are sent BEFORE the transfer takes place (just after the initial PWD command in an FTP transfer, to be exact). To make commands take place after a successful transfer, prefix them with a dash '-'. To make commands be sent after libcurl has changed the working directory, just before the transfer command(s), prefix the command with a '+' (this is only supported for FTP). You may specify any number 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 to FTP servers, or one of the commands listed below to SFTP servers. This option can be used multiple times.
--random-file <file> (SSL) 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/SFTP/FILE) Retrieve a byte range (i.e a partial document) from a HTTP/1.1, FTP or SFTP server or a local FILE. Ranges can be specified in a number of ways.
--raw When used, it disables all internal HTTP decoding of content or transfer encodings and instead makes them passed on unaltered, raw. (Added in 7.16.2)
-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
--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.
--retry-delay <seconds> Make curl sleep this amount of time before each retry when a transfer has failed with a transient error (it changes the default backoff time algorithm between retries). This option is only interesting if --retry is also used. Setting this delay to zero will make curl use the default backoff time. (Added in 7.12.3)
--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).
-s/--silent Silent or quiet mode. Don't show progress meter or error messages. Makes Curl mute
-S/--show-error When used with -s it makes curl show an error message if it fails.
--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).
--socks4a <host[:port]> Use the specified SOCKS4a proxy. If the port number is not specified, it is assumed at port 1080. (Added in 7.18.0)
--socks5-hostname <host[:port]> Use the specified SOCKS5 proxy (and let the proxy resolve the host name). If the port number is not specified, it is assumed at port 1080. (Added in 7.18.0)
--socks5 <host[:port]> Use the specified SOCKS5 proxy - but resolve the host name locally. If the port number is not specified, it is assumed at port 1080.
--socks5-gssapi-service <servicename> The default service name for a socks server is rcmd/server-fqdn. This option allows you to change it
--socks5-gssapi-nec As part of the gssapi negotiation a protection mode is negotiated. The rfc1961 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 protection mode negotiation. (Added in 7.19.4).
--stderr <file> Redirect all writes to stderr to the specified file instead. If the file name is a plain '-', it is instead written to stdout. This option has no point when you're using a shell with decent redirecting capabilities.
--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)
-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. .
--trace <file> Enables a full trace dump of all incoming and outgoing data, including descriptive information, to the given output file. Use "-" as filename to have the output sent to stdout. This option overrides previous uses of -v/--verbose or --trace-ascii.
--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.
--trace-time Prepends a time stamp to each trace or verbose line that curl displays. (Added in 7.14.0)
-u/--user <user:password> Specify the user name and password to use for server authentication. Overrides -n/--netrc and --netrc-optional.
-U/--proxy-user <user:password> Specify the user name and password to use for proxy authentication. If you use an SSPI-enabled curl binary and do NTLM authentication, 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 :"..
--url <URL> Specify a URL to fetch. This option is mostly handy when you want to specify URL(s) in a config file. This option may be used any number of times. To control where this URL is written, use the -o/--output or the -O/--remote-name options
-v/--verbose Makes the fetching more verbose/talkative. Mostly useful for debugging. A line starting with '>' means "header data" sent by curl, '<' means "header data" received by curl that is hidden in normal cases, and a line starting with '*' means additional info provided by curl.
-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.
-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 "@-".
-x/--proxy <proxyhost[:port]> Use the specified HTTP proxy. If the port number is not specified, it is assumed at port 1080.
-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. Common additional HTTP requests include PUT and DELETE, but related technologies like WebDAV offers PROPFIND, COPY, MOVE and more.
-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.
-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.
-z/--time-cond <date expression> (HTTP/FTP) Request a file that has been modified later than the given time and date, or one that has been modified before that time. The date expression can be all sorts of date strings or if it doesn't match any internal ones, it tries to get the time from a given file name instead! See the curl_getdate(3) man pages for date expression details
--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.
--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 (SSL) Forces curl to use TLS version 1 when negotiating with a remote TLS server
-2/--sslv2 (SSL) Forces curl to use SSL version 2 when negotiating with a remote SSL server
-3/--sslv3 (SSL) Forces curl to use SSL version 3 when negotiating with a remote SSL server.
-4/--ipv4 If 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.

EXAMPLES

EXAMPLE-1:

The curl command can be used to download files from the internet but in its basic form you can download the web page content straight to the terminal window.

$ curl http://linux.about.com/cs/linux101/g/curl.htm

output:

% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
0 0 0 0 0 0 0 0 --:--:-- 0:00:01 --:--:-- 0

EXAMPLE-2:

To save the content of curl to a file

$ curl -o <filenametocreate> <URL>

$ curl -o curl.htm http://linux.about.com/cs/linux101/g/curl.htm

output:

% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
0 0 0 0 0 0 0 0 --:--:-- 0:00:01 --:--:-- 0

EXAMPLE-3:

Run The Curl Command In The Background:

To run a command silently use the following command:

$ curl -s -O <URL>

To get the command to run in the background you then need to use the ampersand (&) as follows:

$ curl -s -O <URL> & $ curl -o curl.htm http://linux.about.com/cs/linux101/g/curl.htm &

it will run in the background.


EXAMPLE-4:

To Fetch Multiple Files at a time:

We can download multiple files in a single shot by specifying the URLs on the command line.
Syntax:

$ curl -O URL1 -O URL2
$ curl -O http://www.gnu.org/software/gettext/manual/html_node/index.html -O http://www.gnu.org/software/gettext/manual/gettext.html
 

EXAMPLE-5:

To Limit the Rate of Data Transfer

You can limit the amount at which the data gets transferred using –limit-rate option. You can specify the maximum transfer rate as argument.

$ curl --limit-rate 1000B -O http://www.gnu.org/software/gettext/manual/gettext.html

output:
% Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  1 1215k    1 13601    0     0    957      0  0:21:40  0:00:14  0:21:26   999
  1 1215k    1 14601    0     0    960      0  0:21:36  0:00:15  0:21:21   999
  1 1215k    1 15601    0     0    962      0  0:21:34  0:00:16  0:21:18   999
 

EXAMPLE-6:

To Download Files from FTP server

cURL can also be used to download files from FTP servers. If the given FTP path is a directory, by default it will list the files under the specific directory.

$ curl -u ftpuser:ftppass -O ftp://ftp_server/public_html/xss.php

The above command will download the xss.php file from the ftp server and save it in the local directory.


EXAMPLE-7:

To Upload Files to FTP Server

Curl can also be used to upload files to the FTP server with -T option.

$ curl -u ftpuser:ftppass -T myfile.txt ftp://ftp.testserver.com

The above command will upload the file named myfile.txt to the FTP server

 

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