curl
cURL is a computer software project providing a library and command-line tool for transferring data using various protocols. The cURL project produces two products, libcurl and cURL. It was first released in 1997.
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A free client-side URL transfer library, supporting FTP, FTPS, Gopher (protocol), HTTP, HTTPS, SCP, SFTP, TFTP,TELNET, DICT, FILE, LDAP, LDAPS, IMAP, POP3, SMTP and RTSP (the last four-only in versions newer than 7.20.0 or 9 February 2010). libcurl supports HTTPS certificates, HTTP POST, HTTP PUT, FTP uploading, kerberos, HTTP form based upload, proxies, cookies, user+password authentication, file transfer resume, http proxy tunneling and more.
libcurl is portable. It builds and works identically on several platforms, including Solaris, NetBSD, FreeBSD, OpenBSD, Darwin, HPUX, IRIX, AIX, Tru64, Linux, UnixWare, HURD, Windows, Symbian, Amiga, OS/2, BeOS, Mac OS X, Ultrix, QNX, OpenVMS, RISC OS, Novell NetWare, DOS and more.
libcurl is free, thread-safe, IPv6 compatible, and fast. Bindings in more than 40 languages are available for libcurl.
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A command line tool for getting or sending files using URL syntax.
Since cURL uses libcurl, it supports a range of common Internet protocols, currently including HTTP, HTTPS, FTP, FTPS, SCP, SFTP, TFTP, LDAP, LDAPS, DICT, TELNET, FILE . IMAP, POP3, SMTP and RTSP (the last four-only in versions newer than 7.20.0 or 9 February 2010).
The name of the project is a play on 'Client for URLs', originally with URL spelled in uppercase to make it obvious that it deals with URLs. The fact it can also be pronounced 'see URL' also helped; it works as an abbreviation for "Client URL Request Library" or the recursive version: "Curl URL Request Library".
Daniel Stenberg started writing cURL in 1997, as a way to transfer files via protocols such as http, ftp, gopher, and many more, via a command-line interface. Several other people made important and crucial contributions to the project. Distributed under the MIT License, cURL is free software.
[edit]Examples of cURL use from command line
Basic use of cURL involves simply typing curl at the command line, followed by the URL of the output to retrieve.
To retrieve the example.com homepage, type:
curl www.example.com
cURL defaults to displaying the output it retrieves to the standard output specified on the system (usually the terminal window). So running the command above would, on most systems, display the www.example.com source-code in the terminal window.
cURL can write the output it retrieves to a file with the -o flag, thus:
curl -o example.html www.example.com
This will store the source code for www.example.com into a file named example.html. While retrieving output, cURL will display a progress-bar showing how much of the output has downloaded. Note however that cURL does not show a progress bar when preparing to display the output in the terminal window, since a progress-bar is likely to interfere with the display of the output.
To download output to a file that has the same name as on the system it originates from, use the -O flag:
curl -O (URL)