curl man page

c

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(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.
See also the -A/–user-agent and -e/–referer options.
This option can be used multiple times to add/replace/remove multiple headers.
-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
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
-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 basicly have the same effect as if a new session is started. Typical browsers always discard session cookies when they’re closed down. 9. 7)
-k/–insecure
(SSL) This option explicitly allows curl to perform “insecure” SSL connections and transfers. Starting with curl 7. 10, all SSL connections will be 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
(SSL) Private key file name. Allows you to provide your private key in this separate file.
–key-type
(SSL) Private key file type. Specify which type your –key provided private key is. DER, PEM and ENG are supported.
–krb4
(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 requiures that the library was built with kerberos4 support. This is not very common. Use -V/–version to see if your curl supports it.
-K/–config
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 inclosed 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 = ”
–limit-rate
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/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 rate-limiting slightly, to help keeping the speed-limit logic working.
This option was introduced in curl 7. 10.
-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.
-L/–location
(HTTP/HTTPS) If the server reports that the requested page has a different location (indicated with the header line Location:) this flag will let curl attempt to reattempt the get on the new place. If used together with -i/–include or -I/–head, headers from all requested pages will be shown. If authentication is used, curl will only send its credentials to the initial host, so if a redirect takes curl to a different host, it won’t intercept the user+password. See also –location-trusted on how to change this.
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).
–max-filesize
Specify the maximum size (in bytes) of a file to download. If the file requested is larger than this value, the transfer will not start and curl will return with exit code 63.
NOTE: The file size is not always known prior to download, and for such files this option has no effect even if the file transfer ends up being larger than this given limit. This concerns both FTP and HTTP transfers.
-m/–max-time
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. This doesn’t work fully in win32 systems. See also the –connect-timeout option.
-M/–manual
Manual. Display the huge help text.
-n/–netrc
Makes curl scan the file in the user’s home directory for login name and password. This is typically used for ftp on unix. If used with, 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 to allow curl to ftp to the machine with user name &zerosp;’myself’ and password ‘secret’ should look similar to:
machine 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 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 aplications. 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 (Added in 7. 6)
This option requiures that the library was built with GSSAPI support. Use -V/–version to see if your version supports GSS-Negotiate.
-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. 6)
If you want to enable NTLM for your proxy authentication, then use –proxy-ntlm.
This option requiures that the library was built with SSL support. Use -V/–version to see if your curl supports NTLM.
-o/–output
Write output to instead of stdout. If you are using {} or [] to fetch multiple documents, you can use ‘#’ followed by a number in the specifier. That variable will be replaced with the current string for the URL being fetched. Like in:
curl {one, two} -o “”
or use several variables like:
curl {site, host}[1-5] -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. )
–pass (SSL) Pass phrase for the private key
–proxy-ntlm
Tells curl to use 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 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

(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.

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. 1” to specify exact IP number
host name
i. e “” to specify machine

(any single-letter string) to make it pick the machine’s default
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 $HOME/ file will not be read and used as a config file.
-Q/–quote
(FTP) Send an arbitrary command to the remote FTP server, by using the QUOTE command of the server. Not all servers support this command, and the set of QUOTE commands are server specific! Quote commands are sent BEFORE the transfer is taking place. To make commands take place after a successful transfer, prefix them with a dash ‘-‘. You may specify any amount of commands to be run before and after the transfer. If the server returns failure for one of the commands, the entire operation will be aborted.
–random-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
(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.
0-499 specifies the first 500 bytes
500-999 specifies the second 500 bytes
-500 specifies the last 500 bytes
9500 specifies the bytes from offset 9500 and forward
0-0, -1 specifies the first and last byte only(*)(H)
500-700, 600-799 specifies 300 bytes from offset 500(H)
100-199, 500-599 specifies two separate 100 bytes ranges(*)(H)
(*) = NOTE that this will cause the server to reply with a multipart response!
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.
-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.
-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 mute.
-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.
–socks
Use the specified SOCKS5 proxy. If the port number is not specified, it is assumed at port 1080. (Option added in 7. 1)
This option overrides any previous use of -x/–proxy, as they are mutually exclusive.
–stderr
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.
-t/–telnet-option
Pass options to the telnet protocol. Supported options are:
TTYPE= Sets the terminal type.
XDISPLOC= Sets the X display location.
NEW_ENV= Sets an environment variable.
-T/–upload-file
This transfers the specified local file to the remote URL. If there is no file part in the specified URL, Curl will append the local file name. NOTE that you must use a trailing / on the last directory to really prove to Curl that there is no file name or curl will think that your last directory name is the remote file name to use. That will most likely cause the upload operation to fail. If this is used on a (s) server, the PUT command will be used.
Use the file name “-” (a single dash) to use stdin instead of a given file.
Before 7. 8, when this option was used several times, the last one was used.
In curl 7. 8 and later, you can specify one -T for each URL on the command line. Each -T + URL pair specifies what to upload and to where. curl also 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}”
or even
curl -T “img[1-1000]”
–trace
Enables a full trace dump of all incoming and outgoing data, including descriptive information, to the given output file. Use “-” as filename to have the output sent to stdout.
If this option is used several times, the last one will be used. 7)
–trace-ascii
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.
-u/–user
Specify user and password to use for server authentication.
-U/–proxy-user
Specify user and password to use for proxy authentication.
–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 data sent by curl, ‘<' means data received by curl that is hidden in normal cases and lines starting with '*' means additional info provided by curl. Note that if you want to see 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 authenticaion is supported. GSS-Negotiate Negotiate authenticaion is supported. Debug This curl uses a libcurl built with Debug. This enables more error-tracking and memory debugging etc. For curl-developers only! AsynchDNS This curl uses asynchronous name resolves. SPNEGO SPNEGO Negotiate authenticaion is supported. Largefile This curl supports transfers of large files, files larger than 2GB. -w/--write-out Defines what to display 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_name} 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 space with t.
NOTE: The%-letter is a special letter in the win32-environment, where all occurrences of% must be doubled when using this option.” alt=”What is curl switch?” title=”What is curl switch?” />

What is curl switch?

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How does curl command work?

How does curl command work?

curl is a command line tool to transfer data to or from a server, using any of the supported protocols (HTTP, FTP, IMAP, POP3, SCP, SFTP, SMTP, TFTP, TELNET, LDAP or FILE). curl is powered by Libcurl….-T : This option helps to upload a file to the FTP server. … -x, –proxy : curl also lets us use a proxy to access the URL.More items…•May 15, 2019
What are curl flags?

What are curl flags?

A flag is a command-line parameter that denotes a specific action in Curl. Curl has over three hundred command-line options, and the number of options increases over time. You can add the listed flags to the Curl command and enter the URL. Flags can be short (like o, -L, etc.) or extended (like –verbose).Aug 15, 2021

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