cURL

Not to be confused with Curl, a programming language with a similar name.

For other uses, see Curl (disambiguation).

cURL

Example output from curl -O
Original author(s)	Daniel Stenberg
Developer(s)	Contributors to the cURL project
Initial release	1997 (1997)
Written in	C
Engine
Operating system	AIX, AmigaOS, BeOS, Chrome NaCl, DOS, DragonFly BSD, FreeBSD, GNU-Darwin, HPUX, Haiku, Hurd, IRIX, Linux, macOS, MiNT, Midnight BSD, Minix, NetBSD, NetWare, Nexenta, OS/2, Open Server, OpenBSD, Plan9, QNX, RISC OS, Solaris, Syllable, Tru64 UNIX, UnixWare, VMS, Windows, z/OS
Platform	IA-32, x64
Type	FTP client / HTTP client
License	Free Software: MIT/X derivate license

Search CURL on Amazon.

cURL (/kɝl/ or /kə:l/) 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. The name stands for "Client URL". The original author and lead developer is the Swedish developer Daniel Stenberg.

libcurl

libcurl is a free client-side URL transfer library, supporting cookies, DICT, FTP, FTPS, Gopher, HTTP (with HTTP/2 support), HTTP POST, HTTP PUT, HTTP proxy tunneling, HTTPS, IMAP, Kerberos, LDAP, POP3, RTSP, SCP, and SMTP. The library supports the file URI scheme, SFTP, Telnet, TFTP, file transfer resume, FTP uploading, HTTP form-based upload, HTTPS certificates, LDAPS, proxies, and user-plus-password authentication.

The libcurl library is portable. It builds and works identically on many platforms, including AIX, AmigaOS, Android, BeOS, BlackBerry Tablet OS and BlackBerry 10, OpenVMS, Darwin, DOS, FreeBSD, HP-UX, HURD, iOS, IRIX, Linux, macOS, NetBSD, NetWare, OpenBSD, OS/2, QNX Neutrino, RISC OS, Solaris, Symbian, Tru64, Ultrix, UnixWare, and Windows.

The libcurl library is free, thread-safe and IPv6 compatible. Bindings are available for more than 40 languages, including C/C++, Java, PHP and Python.

The libcurl library can support axTLS, GnuTLS, mbed TLS, NSS, QSOSSL on IBM i, SChannel on Windows, Secure Transport on macOS and iOS, SSL/TLS through OpenSSL, and wolfSSL.

cURL

cURL is 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, DAP, DICT, TELNET, FILE, IMAP, POP3, SMTP and RTSP (the last four only in versions newer than 7.20.0 or 9 February 2010).

cURL supports HTTPS and performs SSL certificate verification by default when a secure protocol is specified such as HTTPS. When cURL connects to a remote server via HTTPS, it will first obtain the remote server certificate and check against its CA certificate store the validity of the remote server to ensure the remote server is the one it claims to be. Some cURL packages have bundled with CA certificate store file. There are several options to specify CA certificate such as --cacert and --capath. The --cacert option can be used to specify the location of the CA certificate store file. In the Windows platform, if a CA certificate file is not specified, cURL will look for a CA certificate file name “curl-ca-bundle.crt” in the following order:

1. Directory where the cURL program is located.
2. Current working directory.
3. Windows system directory.
4. Windows directory.
5. Directories specified in the %PATH% environment variables.

cURL will return an error message if the remote server is using a self-signed certificate, or if the remote server certificate is not signed by a CA listed in the CA cert file. -k or --insecure option can be used to skip certificate verification. Alternatively, if the remote server is trusted, the remote server CA certificate can be added to the CA certificate store file.

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, for example:

curl -O www.example.com/example.html

If the server responds that the file (example.html) is moved to a different location (indicated with a Location: header and a 3XX response code), use the -L flag, for example:

curl -OL www.example.com/example.html

cURL can connect to a remote server via HTTPS protocol (return error message if a CA certificate file cannot be located)

curl https://securesite.com/login.html

To specify a CA certificate file:

curl --cacert c:\temp\cacerts.crt https://securesite.com/login.html

To skip certificate verification:

curl --insecure https://self-signed-cert.com/login.html

Curl offers many other features, including proxy support, user authentication, FTP upload, HTTP post, SSL connections, cookies, file transfer resume, and Metalink.

See also

Some use of "" in your query was not closed by a matching "".Some use of "" in your query was not closed by a matching "".

• curl-loader - an open-source testing tool based on cURL
• libwww
• Wget
• Web crawler
• Powershell iwr

External links

• Official website
• Comparison of cURL vs other open source download tools
• Comparison of cURL vs wget

This article "CURL" is from Wikipedia. The list of its authors can be seen in its historical and/or the page Edithistory:CURL. Articles copied from Draft Namespace on Wikipedia could be seen on the Draft Namespace of Wikipedia and not main one.

This page exists already on Wikipedia.

---