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cURL (pronounced like "curl",<ref name = "FAQ, haxx.se" /> Template:IPAc-en) is a free and open source computer program for transferring data to and from Internet servers using various network protocols. It can download a URL from a web server over HTTP, and supports a variety of other network protocols, URI schemes, multiple versions of HTTP, and proxying. The project consists of both a library (libcurl) and command-line tool (curl), which have been widely ported to different computing platforms.
It was created by Daniel Stenberg, who is still the lead developer of the project.
HistoryEdit
The software was first released in 1996,<ref name="RelFirst">{{#invoke:citation/CS1|citation |CitationClass=web }} </ref> originally named httpget and then became urlget, before adopting the current name of curl.<ref name = "cURL changelog, 2020" /><ref name = "Stenberg, Haxx SE, 2020" /> The name stands for "Client for URL".<ref name="Stenberg, haxx.se, 2018" /> The original author and lead developer is the Swedish developer Daniel Stenberg, who created curl to power part of an IRC bot, because he wanted to automatically provide currency exchange rates, fetched from a website, to users in an IRC chat room.<ref name=history/>
ComponentsEdit
libcurlEdit
libcurl is a client-side URL transfer library that powers curl,<ref name="BlueOne" /> supporting DICT, FTP, FTPS, Gopher, HTTP/1<ref name = "Stenberg, GitHub, 2019" /> (with HTTP/2 and HTTP/3 support), HTTP cookies, HTTP POST, HTTP PUT, HTTP proxy tunneling, HTTPS, IMAP, Kerberos, LDAP, MQTT, POP3, RTSP, RTMP, SCP, SMTP, and SMB. 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.<ref name=curl1>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
The libcurl library is portable, as it builds and works identically on most platforms, including AIX, AmigaOS, Android,Template:Citation needed BeOS, BlackBerry Tablet OS and BlackBerry 10,<ref name = "Blackberry, GitHub" /> 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, Microsoft Windows and OpenHarmony.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name = "Microsoft Techcommunity" />
The libcurl library is thread-safe and IPv6 compatible. Bindings are available for more than 50 languages, including C/C++, Java, Julia (is bundled with), PHP and Python.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
The libcurl library supports GnuTLS, mbed TLS, NSS, Template:Proper name on IBM i, SChannel on Windows, Secure Transport on macOS and iOS, SSL/TLS through OpenSSL, BoringSSL, libreSSL, AmiSSL, wolfSSL, BearSSL and Template:Proper name.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
curlEdit
curl is a command-line tool for getting or sending data including files using URL syntax. curl provides an interface to the libcurl library; it supports every protocol libcurl supports.<ref name=curl1/>
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 obtain the remote server certificate, then 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 are bundled with CA certificate store file. There are several options to specify a CA certificate such as Template:Mono and Template:Mono. The Template:Mono 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:
- Directory where the curl program is located.
- Current working directory.
- Windows system directory.
- Windows directory.
- Directories specified in the %PATH% environment variables.<ref name = "SSL, haxx.se" />
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. Template:Mono or Template:Mono 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.
See alsoEdit
- curl-loader – an open-source testing tool based on curl
- libwww – an early library that comes with a command line interface
- PowerShell – the iwr (Invoke-WebRequest) Windows PowerShell had functionality similar to curl; class Web-client too.<ref name = "Ryan, Ryandel, 2018" />
- Web crawler – an internet bot that can crawl the web
- Wget – similar command-line tool with no associated library but capable of recursive downloading