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<!DOCTYPE HTML> <html lang="en" class="light" dir="ltr"> <head>  <meta charset="UTF-8"> <title>Drive with multi - everything curl</title>  <meta name="description" content="everything there is to know about curl, libcurl and the cURL project"> <meta name="viewport" content="width=device-width, initial-scale=1"> <meta name="theme-color" content="#ffffff"> <link rel="icon" href="../../favicon.svg"> <link rel="shortcut icon" href="../../favicon.png"> <link rel="stylesheet" href="../../css/variables.css"> <link rel="stylesheet" href="../../css/general.css"> <link rel="stylesheet" href="../../css/chrome.css"> <link rel="stylesheet" href="../../css/print.css" media="print">  <link rel="stylesheet" href="../../FontAwesome/css/font-awesome.css"> <link rel="stylesheet" href="../../fonts/fonts.css">  <link rel="stylesheet" href="../../highlight.css"> <link rel="stylesheet" href="../../tomorrow-night.css"> <link rel="stylesheet" href="../../ayu-highlight.css">  </head> <body class="sidebar-visible no-js"> <div id="body-container">  <script> var path_to_root = "../../"; var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "navy" : "light"; </script>  <script> try { var theme = localStorage.getItem('mdbook-theme'); var sidebar = localStorage.getItem('mdbook-sidebar'); if (theme.startsWith('"') && theme.endsWith('"')) { localStorage.setItem('mdbook-theme', theme.slice(1, theme.length - 1)); } if (sidebar.startsWith('"') && sidebar.endsWith('"')) { localStorage.setItem('mdbook-sidebar', sidebar.slice(1, sidebar.length - 1)); } } catch (e) { } </script>  <script> var theme; try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { } if (theme === null || theme === undefined) { theme = default_theme; } var html = document.querySelector('html'); html.classList.remove('light') html.classList.add(theme); var body = document.querySelector('body'); body.classList.remove('no-js') body.classList.add('js'); </script> <input type="checkbox" id="sidebar-toggle-anchor" class="hidden">  <script> var body = document.querySelector('body'); var sidebar = null; var sidebar_toggle = document.getElementById("sidebar-toggle-anchor"); if (document.body.clientWidth >= 1080) { try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { } sidebar = sidebar || 'visible'; } else { sidebar = 'hidden'; } sidebar_toggle.checked = sidebar === 'visible'; body.classList.remove('sidebar-visible'); body.classList.add("sidebar-" + sidebar); </script> <nav id="sidebar" class="sidebar" aria-label="Table of contents"> <div class="sidebar-scrollbox"> <ol class="chapter"><li class="chapter-item "><a href="../../index.html"><strong aria-hidden="true">1.</strong> Introduction</a></li><li class="chapter-item "><a href="../../how-to-read.html"><strong aria-hidden="true">2.</strong> How to read</a></li><li class="chapter-item "><a href="../../project/index.html"><strong aria-hidden="true">3.</strong> The cURL project</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../project/started.html"><strong aria-hidden="true">3.1.</strong> How it started</a></li><li class="chapter-item "><a href="../../project/name.html"><strong aria-hidden="true">3.2.</strong> The name</a></li><li class="chapter-item "><a href="../../project/does.html"><strong aria-hidden="true">3.3.</strong> What does curl do?</a></li><li class="chapter-item "><a href="../../project/comm.html"><strong aria-hidden="true">3.4.</strong> Project communication</a></li><li class="chapter-item "><a href="../../project/etiquette.html"><strong aria-hidden="true">3.5.</strong> Mailing list etiquette</a></li><li class="chapter-item "><a href="../../project/maillists.html"><strong aria-hidden="true">3.6.</strong> Mailing lists</a></li><li class="chapter-item "><a href="../../project/bugs.html"><strong aria-hidden="true">3.7.</strong> Reporting bugs</a></li><li class="chapter-item "><a href="../../project/support.html"><strong aria-hidden="true">3.8.</strong> Commercial support</a></li><li class="chapter-item "><a href="../../project/releases.html"><strong aria-hidden="true">3.9.</strong> Releases</a></li><li class="chapter-item "><a href="../../project/security.html"><strong aria-hidden="true">3.10.</strong> Security</a></li><li class="chapter-item "><a href="../../project/trust.html"><strong aria-hidden="true">3.11.</strong> Trust</a></li><li class="chapter-item "><a href="../../project/coc.html"><strong aria-hidden="true">3.12.</strong> Code of Conduct</a></li><li class="chapter-item "><a href="../../project/devel.html"><strong aria-hidden="true">3.13.</strong> Development</a></li><li class="chapter-item "><a href="../../project/devteam.html"><strong aria-hidden="true">3.14.</strong> The development team</a></li><li class="chapter-item "><a href="../../project/users.html"><strong aria-hidden="true">3.15.</strong> Users of curl</a></li><li class="chapter-item "><a href="../../project/future.html"><strong aria-hidden="true">3.16.</strong> Future</a></li></ol></li><li class="chapter-item "><a href="../../protocols/index.html"><strong aria-hidden="true">4.</strong> Network and protocols</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../protocols/network.html"><strong aria-hidden="true">4.1.</strong> Networking simplified</a></li><li class="chapter-item "><a href="../../protocols/protocols.html"><strong aria-hidden="true">4.2.</strong> Protocols</a></li><li class="chapter-item "><a href="../../protocols/curl.html"><strong aria-hidden="true">4.3.</strong> curl protocols</a></li><li class="chapter-item "><a href="../../protocols/http.html"><strong aria-hidden="true">4.4.</strong> HTTP basics</a></li></ol></li><li class="chapter-item "><a href="../../install/index.html"><strong aria-hidden="true">5.</strong> Install curl and libcurl</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../install/linux.html"><strong aria-hidden="true">5.1.</strong> Linux</a></li><li class="chapter-item "><a href="../../install/windows/index.html"><strong aria-hidden="true">5.2.</strong> Windows</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../install/windows/win-msys2.html"><strong aria-hidden="true">5.2.1.</strong> MSYS2</a></li><li class="chapter-item "><a href="../../install/windows/win-vcpkg.html"><strong aria-hidden="true">5.2.2.</strong> vcpkg</a></li></ol></li><li class="chapter-item "><a href="../../install/macos.html"><strong aria-hidden="true">5.3.</strong> macOS</a></li><li class="chapter-item "><a href="../../install/container.html"><strong aria-hidden="true">5.4.</strong> Container</a></li></ol></li><li class="chapter-item "><a href="../../source/index.html"><strong aria-hidden="true">6.</strong> Source code</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../source/opensource/index.html"><strong aria-hidden="true">6.1.</strong> Open Source</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../source/opensource/license.html"><strong aria-hidden="true">6.1.1.</strong> License</a></li><li class="chapter-item "><a href="../../source/opensource/copyright.html"><strong aria-hidden="true">6.1.2.</strong> Copyright</a></li></ol></li><li class="chapter-item "><a href="../../source/layout.html"><strong aria-hidden="true">6.2.</strong> Code layout</a></li><li class="chapter-item "><a href="../../source/options.html"><strong aria-hidden="true">6.3.</strong> Handling build options</a></li><li class="chapter-item "><a href="../../source/style.html"><strong aria-hidden="true">6.4.</strong> Code style</a></li><li class="chapter-item "><a href="../../source/contributing.html"><strong aria-hidden="true">6.5.</strong> Contributing</a></li><li class="chapter-item "><a href="../../source/reportvuln.html"><strong aria-hidden="true">6.6.</strong> Reporting vulnerabilities</a></li><li class="chapter-item "><a href="../../source/web.html"><strong aria-hidden="true">6.7.</strong> Website</a></li></ol></li><li class="chapter-item "><a href="../../build/index.html"><strong aria-hidden="true">7.</strong> Build curl and libcurl</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../build/autotools.html"><strong aria-hidden="true">7.1.</strong> Autotools</a></li><li class="chapter-item "><a href="../../build/cmake.html"><strong aria-hidden="true">7.2.</strong> CMake</a></li><li class="chapter-item "><a href="../../build/separate.html"><strong aria-hidden="true">7.3.</strong> Separate install</a></li><li class="chapter-item "><a href="../../build/windows.html"><strong aria-hidden="true">7.4.</strong> Windows</a></li><li class="chapter-item "><a href="../../build/deps.html"><strong aria-hidden="true">7.5.</strong> Dependencies</a></li><li class="chapter-item "><a href="../../build/tls.html"><strong aria-hidden="true">7.6.</strong> TLS libraries</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../build/boringssl.html"><strong aria-hidden="true">7.6.1.</strong> BoringSSL</a></li></ol></li></ol></li><li class="chapter-item "><a href="../../cmdline/index.html"><strong aria-hidden="true">8.</strong> Command line concepts</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../cmdline/differences.html"><strong aria-hidden="true">8.1.</strong> Differences</a></li><li class="chapter-item "><a href="../../cmdline/options/index.html"><strong aria-hidden="true">8.2.</strong> Command line options</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../cmdline/options/short.html"><strong aria-hidden="true">8.2.1.</strong> Short options</a></li><li class="chapter-item "><a href="../../cmdline/options/long.html"><strong aria-hidden="true">8.2.2.</strong> Long options</a></li><li class="chapter-item "><a href="../../cmdline/options/args.html"><strong aria-hidden="true">8.2.3.</strong> Arguments to options</a></li><li class="chapter-item "><a href="../../cmdline/options/negative.html"><strong aria-hidden="true">8.2.4.</strong> Negative options</a></li></ol></li><li class="chapter-item "><a href="../../cmdline/versions.html"><strong aria-hidden="true">8.3.</strong> Options depend on version</a></li><li class="chapter-item "><a href="../../cmdline/urls/index.html"><strong aria-hidden="true">8.4.</strong> URLs</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../cmdline/urls/scheme.html"><strong aria-hidden="true">8.4.1.</strong> Scheme</a></li><li class="chapter-item "><a href="../../cmdline/urls/auth.html"><strong aria-hidden="true">8.4.2.</strong> Name and password</a></li><li class="chapter-item "><a href="../../cmdline/urls/host.html"><strong aria-hidden="true">8.4.3.</strong> Host</a></li><li class="chapter-item "><a href="../../cmdline/urls/port.html"><strong aria-hidden="true">8.4.4.</strong> Port number</a></li><li class="chapter-item "><a href="../../cmdline/urls/path.html"><strong aria-hidden="true">8.4.5.</strong> Path</a></li><li class="chapter-item "><a href="../../cmdline/urls/query.html"><strong aria-hidden="true">8.4.6.</strong> Query</a></li><li class="chapter-item "><a href="../../cmdline/urls/ftptype.html"><strong aria-hidden="true">8.4.7.</strong> FTP type</a></li><li class="chapter-item "><a href="../../cmdline/urls/fragment.html"><strong aria-hidden="true">8.4.8.</strong> Fragment</a></li><li class="chapter-item "><a href="../../cmdline/urls/browsers.html"><strong aria-hidden="true">8.4.9.</strong> Browsers</a></li><li class="chapter-item "><a href="../../cmdline/urls/options.html"><strong aria-hidden="true">8.4.10.</strong> Many options and URLs</a></li><li class="chapter-item "><a href="../../cmdline/urls/globbing.html"><strong aria-hidden="true">8.4.11.</strong> URL globbing</a></li><li class="chapter-item "><a href="../../cmdline/urls/connreuse.html"><strong aria-hidden="true">8.4.12.</strong> Connection reuse</a></li><li class="chapter-item "><a href="../../cmdline/urls/parallel.html"><strong aria-hidden="true">8.4.13.</strong> Parallel transfers</a></li><li class="chapter-item "><a href="../../cmdline/urls/trurl.html"><strong aria-hidden="true">8.4.14.</strong> trurl</a></li></ol></li><li class="chapter-item "><a href="../../cmdline/listopts.html"><strong aria-hidden="true">8.5.</strong> List options</a></li><li class="chapter-item "><a href="../../cmdline/configfile.html"><strong aria-hidden="true">8.6.</strong> Config file</a></li><li class="chapter-item "><a href="../../cmdline/variables.html"><strong aria-hidden="true">8.7.</strong> Variables</a></li><li class="chapter-item "><a href="../../cmdline/passwords.html"><strong aria-hidden="true">8.8.</strong> Passwords</a></li><li class="chapter-item "><a href="../../cmdline/progressmeter.html"><strong aria-hidden="true">8.9.</strong> Progress meter</a></li><li class="chapter-item "><a href="../../cmdline/curlver.html"><strong aria-hidden="true">8.10.</strong> Version</a></li><li class="chapter-item "><a href="../../cmdline/exitcode.html"><strong aria-hidden="true">8.11.</strong> Exit code</a></li><li class="chapter-item "><a href="../../cmdline/copyas.html"><strong aria-hidden="true">8.12.</strong> Copy as curl</a></li></ol></li><li class="chapter-item "><a href="../../usingcurl/index.html"><strong aria-hidden="true">9.</strong> Command line transfers</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../usingcurl/verbose/index.html"><strong aria-hidden="true">9.1.</strong> Verbose</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../usingcurl/verbose/trace.html"><strong aria-hidden="true">9.1.1.</strong> Trace options</a></li><li class="chapter-item "><a href="../../usingcurl/verbose/writeout.html"><strong aria-hidden="true">9.1.2.</strong> Write out</a></li></ol></li><li class="chapter-item "><a href="../../usingcurl/downloads/index.html"><strong aria-hidden="true">9.2.</strong> Downloads</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../usingcurl/downloads/whatis.html"><strong aria-hidden="true">9.2.1.</strong> What is downloading?</a></li><li class="chapter-item "><a href="../../usingcurl/downloads/storing.html"><strong aria-hidden="true">9.2.2.</strong> Storing downloads</a></li><li class="chapter-item "><a href="../../usingcurl/downloads/url-named.html"><strong aria-hidden="true">9.2.3.</strong> Download to a file named by the URL</a></li><li class="chapter-item "><a href="../../usingcurl/downloads/content-disp.html"><strong aria-hidden="true">9.2.4.</strong> Use the target filename from the server</a></li><li class="chapter-item "><a href="../../usingcurl/downloads/charsets.html"><strong aria-hidden="true">9.2.5.</strong> HTML and charsets</a></li><li class="chapter-item "><a href="../../usingcurl/downloads/redirects.html"><strong aria-hidden="true">9.2.6.</strong> Shell redirects</a></li><li class="chapter-item "><a href="../../usingcurl/downloads/multiple.html"><strong aria-hidden="true">9.2.7.</strong> Multiple downloads</a></li><li class="chapter-item "><a href="../../usingcurl/downloads/browsers.html"><strong aria-hidden="true">9.2.8.</strong> My browser shows something else</a></li><li class="chapter-item "><a href="../../usingcurl/downloads/max-filesize.html"><strong aria-hidden="true">9.2.9.</strong> Maximum filesize</a></li><li class="chapter-item "><a href="../../usingcurl/downloads/metadata-fs.html"><strong aria-hidden="true">9.2.10.</strong> Storing metadata in file system</a></li><li class="chapter-item "><a href="../../usingcurl/downloads/raw.html"><strong aria-hidden="true">9.2.11.</strong> Raw</a></li><li class="chapter-item "><a href="../../usingcurl/downloads/retry.html"><strong aria-hidden="true">9.2.12.</strong> Retry</a></li><li class="chapter-item "><a href="../../usingcurl/downloads/resume.html"><strong aria-hidden="true">9.2.13.</strong> Resuming and ranges</a></li></ol></li><li class="chapter-item "><a href="../../usingcurl/uploads.html"><strong aria-hidden="true">9.3.</strong> Uploads</a></li><li class="chapter-item "><a href="../../usingcurl/transfers/index.html"><strong aria-hidden="true">9.4.</strong> Transfer controls</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../usingcurl/transfers/tooslow.html"><strong aria-hidden="true">9.4.1.</strong> Stop slow transfers</a></li><li class="chapter-item "><a href="../../usingcurl/transfers/rate-limiting.html"><strong aria-hidden="true">9.4.2.</strong> Rate limiting</a></li><li class="chapter-item "><a href="../../usingcurl/transfers/request-rate.html"><strong aria-hidden="true">9.4.3.</strong> Request rate limiting</a></li><li class="chapter-item "><a href="../../usingcurl/transfers/compression.html"><strong aria-hidden="true">9.4.4.</strong> Compression</a></li></ol></li><li class="chapter-item "><a href="../../usingcurl/connections/index.html"><strong aria-hidden="true">9.5.</strong> Connections</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../usingcurl/connections/name.html"><strong aria-hidden="true">9.5.1.</strong> Name resolve tricks</a></li><li class="chapter-item "><a href="../../usingcurl/connections/timeout.html"><strong aria-hidden="true">9.5.2.</strong> Connection timeout</a></li><li class="chapter-item "><a href="../../usingcurl/connections/happy.html"><strong aria-hidden="true">9.5.3.</strong> Happy Eyeballs</a></li><li class="chapter-item "><a href="../../usingcurl/connections/interface.html"><strong aria-hidden="true">9.5.4.</strong> Network interface</a></li><li class="chapter-item "><a href="../../usingcurl/connections/local-port.html"><strong aria-hidden="true">9.5.5.</strong> Local port number</a></li><li class="chapter-item "><a href="../../usingcurl/connections/keepalive.html"><strong aria-hidden="true">9.5.6.</strong> Keep alive</a></li></ol></li><li class="chapter-item "><a href="../../usingcurl/timeouts.html"><strong aria-hidden="true">9.6.</strong> Timeouts</a></li><li class="chapter-item "><a href="../../usingcurl/netrc.html"><strong aria-hidden="true">9.7.</strong> .netrc</a></li><li class="chapter-item "><a href="../../usingcurl/proxies/index.html"><strong aria-hidden="true">9.8.</strong> Proxies</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../usingcurl/proxies/discover.html"><strong aria-hidden="true">9.8.1.</strong> Discover your proxy</a></li><li class="chapter-item "><a href="../../usingcurl/proxies/pac.html"><strong aria-hidden="true">9.8.2.</strong> PAC</a></li><li class="chapter-item "><a href="../../usingcurl/proxies/captive.html"><strong aria-hidden="true">9.8.3.</strong> Captive portals</a></li><li class="chapter-item "><a href="../../usingcurl/proxies/type.html"><strong aria-hidden="true">9.8.4.</strong> Proxy type</a></li><li class="chapter-item "><a href="../../usingcurl/proxies/http.html"><strong aria-hidden="true">9.8.5.</strong> HTTP proxy</a></li><li class="chapter-item "><a href="../../usingcurl/proxies/socks.html"><strong aria-hidden="true">9.8.6.</strong> SOCKS proxy</a></li><li class="chapter-item "><a href="../../usingcurl/proxies/mitm.html"><strong aria-hidden="true">9.8.7.</strong> MITM proxy</a></li><li class="chapter-item "><a href="../../usingcurl/proxies/auth.html"><strong aria-hidden="true">9.8.8.</strong> Proxy authentication</a></li><li class="chapter-item "><a href="../../usingcurl/proxies/https.html"><strong aria-hidden="true">9.8.9.</strong> HTTPS proxy</a></li><li class="chapter-item "><a href="../../usingcurl/proxies/env.html"><strong aria-hidden="true">9.8.10.</strong> Proxy environment variables</a></li><li class="chapter-item "><a href="../../usingcurl/proxies/headers.html"><strong aria-hidden="true">9.8.11.</strong> Proxy headers</a></li><li class="chapter-item "><a href="../../usingcurl/proxies/haproxy.html"><strong aria-hidden="true">9.8.12.</strong> haproxy</a></li></ol></li><li class="chapter-item "><a href="../../usingcurl/tls.html"><strong aria-hidden="true">9.9.</strong> TLS</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../usingcurl/tls/ciphers.html"><strong aria-hidden="true">9.9.1.</strong> Ciphers</a></li><li class="chapter-item "><a href="../../usingcurl/tls/enable.html"><strong aria-hidden="true">9.9.2.</strong> Enable TLS</a></li><li class="chapter-item "><a href="../../usingcurl/tls/versions.html"><strong aria-hidden="true">9.9.3.</strong> TLS versions</a></li><li class="chapter-item "><a href="../../usingcurl/tls/verify.html"><strong aria-hidden="true">9.9.4.</strong> Verifying server certificates</a></li><li class="chapter-item "><a href="../../usingcurl/tls/pinning.html"><strong aria-hidden="true">9.9.5.</strong> Certificate pinning</a></li><li class="chapter-item "><a href="../../usingcurl/tls/stapling.html"><strong aria-hidden="true">9.9.6.</strong> OCSP stapling</a></li><li class="chapter-item "><a href="../../usingcurl/tls/clientcert.html"><strong aria-hidden="true">9.9.7.</strong> Client certificates</a></li><li class="chapter-item "><a href="../../usingcurl/tls/auth.html"><strong aria-hidden="true">9.9.8.</strong> TLS auth</a></li><li class="chapter-item "><a href="../../usingcurl/tls/backends.html"><strong aria-hidden="true">9.9.9.</strong> TLS backends</a></li><li class="chapter-item "><a href="../../usingcurl/tls/sslkeylogfile.html"><strong aria-hidden="true">9.9.10.</strong> SSLKEYLOGFILE</a></li></ol></li><li class="chapter-item "><a href="../../usingcurl/ssh/index.html"><strong aria-hidden="true">9.10.</strong> SCP and SFTP</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../usingcurl/ssh/url.html"><strong aria-hidden="true">9.10.1.</strong> URLs</a></li><li class="chapter-item "><a href="../../usingcurl/ssh/auth.html"><strong aria-hidden="true">9.10.2.</strong> Authentication</a></li><li class="chapter-item "><a href="../../usingcurl/ssh/knownhosts.html"><strong aria-hidden="true">9.10.3.</strong> Known hosts</a></li></ol></li><li class="chapter-item "><a href="../../usingcurl/reademail.html"><strong aria-hidden="true">9.11.</strong> Reading email</a></li><li class="chapter-item "><a href="../../usingcurl/smtp.html"><strong aria-hidden="true">9.12.</strong> Sending email</a></li><li class="chapter-item "><a href="../../usingcurl/dict.html"><strong aria-hidden="true">9.13.</strong> DICT</a></li><li class="chapter-item "><a href="../../usingcurl/ipfs.html"><strong aria-hidden="true">9.14.</strong> IPFS</a></li><li class="chapter-item "><a href="../../usingcurl/mqtt.html"><strong aria-hidden="true">9.15.</strong> MQTT</a></li><li class="chapter-item "><a href="../../usingcurl/telnet.html"><strong aria-hidden="true">9.16.</strong> TELNET</a></li><li class="chapter-item "><a href="../../usingcurl/tftp.html"><strong aria-hidden="true">9.17.</strong> TFTP</a></li></ol></li><li class="chapter-item "><a href="../../http/index.html"><strong aria-hidden="true">10.</strong> Command line HTTP</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../http/method.html"><strong aria-hidden="true">10.1.</strong> Method</a></li><li class="chapter-item "><a href="../../http/response.html"><strong aria-hidden="true">10.2.</strong> Responses</a></li><li class="chapter-item "><a href="../../http/auth.html"><strong aria-hidden="true">10.3.</strong> Authentication</a></li><li class="chapter-item "><a href="../../http/versions/index.html"><strong aria-hidden="true">10.4.</strong> HTTP versions</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../http/versions/http09.html"><strong aria-hidden="true">10.4.1.</strong> HTTP/0.9</a></li><li class="chapter-item "><a href="../../http/versions/http2.html"><strong aria-hidden="true">10.4.2.</strong> HTTP/2</a></li><li class="chapter-item "><a href="../../http/versions/http3.html"><strong aria-hidden="true">10.4.3.</strong> HTTP/3</a></li></ol></li><li class="chapter-item "><a href="../../http/post/index.html"><strong aria-hidden="true">10.5.</strong> HTTP POST</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../http/post/simple.html"><strong aria-hidden="true">10.5.1.</strong> Simple POST</a></li><li class="chapter-item "><a href="../../http/post/content-type.html"><strong aria-hidden="true">10.5.2.</strong> Content-Type</a></li><li class="chapter-item "><a href="../../http/post/binary.html"><strong aria-hidden="true">10.5.3.</strong> Posting binary</a></li><li class="chapter-item "><a href="../../http/post/json.html"><strong aria-hidden="true">10.5.4.</strong> JSON</a></li><li class="chapter-item "><a href="../../http/post/url-encode.html"><strong aria-hidden="true">10.5.5.</strong> URL encode data</a></li><li class="chapter-item "><a href="../../http/post/convert-to-get.html"><strong aria-hidden="true">10.5.6.</strong> Convert to GET</a></li><li class="chapter-item "><a href="../../http/post/expect100.html"><strong aria-hidden="true">10.5.7.</strong> Expect 100-continue</a></li><li class="chapter-item "><a href="../../http/post/chunked.html"><strong aria-hidden="true">10.5.8.</strong> Chunked encoded POSTs</a></li><li class="chapter-item "><a href="../../http/post/hiddenfields.html"><strong aria-hidden="true">10.5.9.</strong> Hidden form fields</a></li><li class="chapter-item "><a href="../../http/post/browsersends.html"><strong aria-hidden="true">10.5.10.</strong> Figure out what a browser sends</a></li><li class="chapter-item "><a href="../../http/post/javascript.html"><strong aria-hidden="true">10.5.11.</strong> JavaScript and forms</a></li><li class="chapter-item "><a href="../../http/post/multipart.html"><strong aria-hidden="true">10.5.12.</strong> Multipart formposts</a></li><li class="chapter-item "><a href="../../http/post/postvspost.html"><strong aria-hidden="true">10.5.13.</strong> -d vs -F</a></li></ol></li><li class="chapter-item "><a href="../../http/put.html"><strong aria-hidden="true">10.6.</strong> HTTP PUT</a></li><li class="chapter-item "><a href="../../http/redirects.html"><strong aria-hidden="true">10.7.</strong> Redirects</a></li><li class="chapter-item "><a href="../../http/modify/index.html"><strong aria-hidden="true">10.8.</strong> Customize your HTTP</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../http/modify/method.html"><strong aria-hidden="true">10.8.1.</strong> Request method</a></li><li class="chapter-item "><a href="../../http/modify/target.html"><strong aria-hidden="true">10.8.2.</strong> Request target</a></li><li class="chapter-item "><a href="../../http/modify/fragment.html"><strong aria-hidden="true">10.8.3.</strong> Fragment</a></li><li class="chapter-item "><a href="../../http/modify/headers.html"><strong aria-hidden="true">10.8.4.</strong> Customize headers</a></li><li class="chapter-item "><a href="../../http/modify/referer.html"><strong aria-hidden="true">10.8.5.</strong> Referer</a></li><li class="chapter-item "><a href="../../http/modify/user-agent.html"><strong aria-hidden="true">10.8.6.</strong> User-agent</a></li><li class="chapter-item "><a href="../../http/modify/ranges.html"><strong aria-hidden="true">10.8.7.</strong> Ranges</a></li><li class="chapter-item "><a href="../../http/modify/conditionals.html"><strong aria-hidden="true">10.8.8.</strong> Conditionals</a></li><li class="chapter-item "><a href="../../http/modify/compression.html"><strong aria-hidden="true">10.8.9.</strong> Compression</a></li></ol></li><li class="chapter-item "><a href="../../http/cookies/index.html"><strong aria-hidden="true">10.9.</strong> Cookies</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../http/cookies/engine.html"><strong aria-hidden="true">10.9.1.</strong> Cookie engine</a></li><li class="chapter-item "><a href="../../http/cookies/reading.html"><strong aria-hidden="true">10.9.2.</strong> Reading cookies from file</a></li><li class="chapter-item "><a href="../../http/cookies/writing.html"><strong aria-hidden="true">10.9.3.</strong> Writing cookies to file</a></li><li class="chapter-item "><a href="../../http/cookies/newsession.html"><strong aria-hidden="true">10.9.4.</strong> New cookie session</a></li><li class="chapter-item "><a href="../../http/cookies/fileformat.html"><strong aria-hidden="true">10.9.5.</strong> Cookie file format</a></li></ol></li><li class="chapter-item "><a href="../../http/https.html"><strong aria-hidden="true">10.10.</strong> HTTPS</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../http/https/hsts.html"><strong aria-hidden="true">10.10.1.</strong> HSTS</a></li><li class="chapter-item "><a href="../../http/https/altsvc.html"><strong aria-hidden="true">10.10.2.</strong> Alternative Services</a></li></ol></li><li class="chapter-item "><a href="../../http/browserlike.html"><strong aria-hidden="true">10.11.</strong> Scripting browser-like tasks</a></li></ol></li><li class="chapter-item "><a href="../../ftp/index.html"><strong aria-hidden="true">11.</strong> Command line FTP</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../ftp/dirlist.html"><strong aria-hidden="true">11.1.</strong> FTP Directory listing</a></li><li class="chapter-item "><a href="../../ftp/upload.html"><strong aria-hidden="true">11.2.</strong> Uploading with FTP</a></li><li class="chapter-item "><a href="../../ftp/cmds.html"><strong aria-hidden="true">11.3.</strong> Custom FTP commands</a></li><li class="chapter-item "><a href="../../ftp/twoconnections.html"><strong aria-hidden="true">11.4.</strong> Two connections</a></li><li class="chapter-item "><a href="../../ftp/traversedir.html"><strong aria-hidden="true">11.5.</strong> Directory traversing</a></li><li class="chapter-item "><a href="../../ftp/ftps.html"><strong aria-hidden="true">11.6.</strong> FTPS</a></li></ol></li><li class="chapter-item "><a href="../../libcurl/index.html"><strong aria-hidden="true">12.</strong> libcurl</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../libcurl/headers.html"><strong aria-hidden="true">12.1.</strong> Header files</a></li><li class="chapter-item "><a href="../../libcurl/globalinit.html"><strong aria-hidden="true">12.2.</strong> Global initialization</a></li><li class="chapter-item "><a href="../../libcurl/api.html"><strong aria-hidden="true">12.3.</strong> API compatibility</a></li><li class="chapter-item "><a href="../../libcurl/--libcurl.html"><strong aria-hidden="true">12.4.</strong> --libcurl</a></li><li class="chapter-item "><a href="../../libcurl/threading.html"><strong aria-hidden="true">12.5.</strong> multi-threading</a></li><li class="chapter-item "><a href="../../libcurl/curlcode.html"><strong aria-hidden="true">12.6.</strong> CURLcode return codes</a></li><li class="chapter-item "><a href="../../libcurl/verbose.html"><strong aria-hidden="true">12.7.</strong> Verbose operations</a></li><li class="chapter-item "><a href="../../libcurl/caches.html"><strong aria-hidden="true">12.8.</strong> Caches</a></li><li class="chapter-item "><a href="../../libcurl/performance.html"><strong aria-hidden="true">12.9.</strong> Performance</a></li><li class="chapter-item "><a href="../../libcurl/cplusplus.html"><strong aria-hidden="true">12.10.</strong> for C++ programmers</a></li></ol></li><li class="chapter-item expanded "><a href="../../transfers/index.html"><strong aria-hidden="true">13.</strong> libcurl transfers</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../transfers/easyhandle.html"><strong aria-hidden="true">13.1.</strong> Easy handle</a></li><li class="chapter-item "><a href="../../transfers/options/index.html"><strong aria-hidden="true">13.2.</strong> curl easy options</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../transfers/options/num.html"><strong aria-hidden="true">13.2.1.</strong> Set numerical options</a></li><li class="chapter-item "><a href="../../transfers/options/strings.html"><strong aria-hidden="true">13.2.2.</strong> Set string options</a></li><li class="chapter-item "><a href="../../transfers/options/tls.html"><strong aria-hidden="true">13.2.3.</strong> TLS options</a></li><li class="chapter-item "><a href="../../transfers/options/all.html"><strong aria-hidden="true">13.2.4.</strong> All options</a></li><li class="chapter-item "><a href="../../transfers/options/info.html"><strong aria-hidden="true">13.2.5.</strong> Get option information</a></li></ol></li><li class="chapter-item expanded "><a href="../../transfers/drive/index.html"><strong aria-hidden="true">13.3.</strong> Drive transfers</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../transfers/drive/easy.html"><strong aria-hidden="true">13.3.1.</strong> Drive with easy</a></li><li class="chapter-item expanded "><a href="../../transfers/drive/multi.html" class="active"><strong aria-hidden="true">13.3.2.</strong> Drive with multi</a></li><li class="chapter-item "><a href="../../transfers/drive/multi-socket.html"><strong aria-hidden="true">13.3.3.</strong> Drive with multi_socket</a></li></ol></li><li class="chapter-item "><a href="../../transfers/callbacks/index.html"><strong aria-hidden="true">13.4.</strong> Callbacks</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../transfers/callbacks/write.html"><strong aria-hidden="true">13.4.1.</strong> Write data</a></li><li class="chapter-item "><a href="../../transfers/callbacks/read.html"><strong aria-hidden="true">13.4.2.</strong> Read data</a></li><li class="chapter-item "><a href="../../transfers/callbacks/progress.html"><strong aria-hidden="true">13.4.3.</strong> Progress information</a></li><li class="chapter-item "><a href="../../transfers/callbacks/header.html"><strong aria-hidden="true">13.4.4.</strong> Header data</a></li><li class="chapter-item "><a href="../../transfers/callbacks/debug.html"><strong aria-hidden="true">13.4.5.</strong> Debug</a></li><li class="chapter-item "><a href="../../transfers/callbacks/sockopt.html"><strong aria-hidden="true">13.4.6.</strong> sockopt</a></li><li class="chapter-item "><a href="../../transfers/callbacks/sslcontext.html"><strong aria-hidden="true">13.4.7.</strong> SSL context</a></li><li class="chapter-item "><a href="../../transfers/callbacks/seek.html"><strong aria-hidden="true">13.4.8.</strong> Seek and ioctl</a></li><li class="chapter-item "><a href="../../transfers/callbacks/conversions.html"><strong aria-hidden="true">13.4.9.</strong> Network data conversion</a></li><li class="chapter-item "><a href="../../transfers/callbacks/openclosesocket.html"><strong aria-hidden="true">13.4.10.</strong> Opensocket and closesocket</a></li><li class="chapter-item "><a href="../../transfers/callbacks/sshkey.html"><strong aria-hidden="true">13.4.11.</strong> SSH key</a></li><li class="chapter-item "><a href="../../transfers/callbacks/rtsp.html"><strong aria-hidden="true">13.4.12.</strong> RTSP interleaved data</a></li><li class="chapter-item "><a href="../../transfers/callbacks/ftpmatch.html"><strong aria-hidden="true">13.4.13.</strong> FTP wildcard matching</a></li><li class="chapter-item "><a href="../../transfers/callbacks/resolver.html"><strong aria-hidden="true">13.4.14.</strong> Resolver start</a></li><li class="chapter-item "><a href="../../transfers/callbacks/trailers.html"><strong aria-hidden="true">13.4.15.</strong> Sending trailers</a></li><li class="chapter-item "><a href="../../transfers/callbacks/hsts.html"><strong aria-hidden="true">13.4.16.</strong> HSTS</a></li><li class="chapter-item "><a href="../../transfers/callbacks/prereq.html"><strong aria-hidden="true">13.4.17.</strong> Prereq</a></li></ol></li><li class="chapter-item "><a href="../../transfers/conn/index.html"><strong aria-hidden="true">13.5.</strong> Connection control</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../transfers/conn/how.html"><strong aria-hidden="true">13.5.1.</strong> How libcurl connects</a></li><li class="chapter-item "><a href="../../transfers/conn/local.html"><strong aria-hidden="true">13.5.2.</strong> Local address and port number</a></li><li class="chapter-item "><a href="../../transfers/conn/reuse.html"><strong aria-hidden="true">13.5.3.</strong> Connection reuse</a></li><li class="chapter-item "><a href="../../transfers/conn/keepalive.html"><strong aria-hidden="true">13.5.4.</strong> Keep alive</a></li><li class="chapter-item "><a href="../../transfers/conn/names.html"><strong aria-hidden="true">13.5.5.</strong> Name resolving</a></li><li class="chapter-item "><a href="../../transfers/conn/proxies.html"><strong aria-hidden="true">13.5.6.</strong> Proxies</a></li></ol></li><li class="chapter-item "><a href="../../transfers/control/index.html"><strong aria-hidden="true">13.6.</strong> Transfer control</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../transfers/control/stop.html"><strong aria-hidden="true">13.6.1.</strong> Stop</a></li><li class="chapter-item "><a href="../../transfers/control/stopslow.html"><strong aria-hidden="true">13.6.2.</strong> Stop slow transfers</a></li><li class="chapter-item "><a href="../../transfers/control/ratelimit.html"><strong aria-hidden="true">13.6.3.</strong> Rate limit</a></li><li class="chapter-item "><a href="../../transfers/control/meter.html"><strong aria-hidden="true">13.6.4.</strong> Progress meter</a></li><li class="chapter-item "><a href="../../transfers/control/progress-callback.html"><strong aria-hidden="true">13.6.5.</strong> Progress callback</a></li></ol></li><li class="chapter-item "><a href="../../transfers/auth.html"><strong aria-hidden="true">13.7.</strong> Authentication</a></li><li class="chapter-item "><a href="../../transfers/cleanup.html"><strong aria-hidden="true">13.8.</strong> Cleanup</a></li><li class="chapter-item "><a href="../../transfers/getinfo.html"><strong aria-hidden="true">13.9.</strong> Post transfer info</a></li></ol></li><li class="chapter-item "><a href="../../libcurl-http/index.html"><strong aria-hidden="true">14.</strong> libcurl HTTP</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../libcurl-http/responses.html"><strong aria-hidden="true">14.1.</strong> Responses</a></li><li class="chapter-item "><a href="../../libcurl-http/requests.html"><strong aria-hidden="true">14.2.</strong> Requests</a></li><li class="chapter-item "><a href="../../libcurl-http/versions.html"><strong aria-hidden="true">14.3.</strong> Versions</a></li><li class="chapter-item "><a href="../../libcurl-http/ranges.html"><strong aria-hidden="true">14.4.</strong> Ranges</a></li><li class="chapter-item "><a href="../../libcurl-http/auth.html"><strong aria-hidden="true">14.5.</strong> Authentication</a></li><li class="chapter-item "><a href="../../libcurl-http/cookies.html"><strong aria-hidden="true">14.6.</strong> Cookies</a></li><li class="chapter-item "><a href="../../libcurl-http/download.html"><strong aria-hidden="true">14.7.</strong> Download</a></li><li class="chapter-item "><a href="../../libcurl-http/upload.html"><strong aria-hidden="true">14.8.</strong> Upload</a></li><li class="chapter-item "><a href="../../libcurl-http/multiplexing.html"><strong aria-hidden="true">14.9.</strong> Multiplexing</a></li><li class="chapter-item "><a href="../../libcurl-http/hsts.html"><strong aria-hidden="true">14.10.</strong> HSTS</a></li><li class="chapter-item "><a href="../../libcurl-http/alt-svc.html"><strong aria-hidden="true">14.11.</strong> alt-svc</a></li></ol></li><li class="chapter-item "><a href="../../helpers/index.html"><strong aria-hidden="true">15.</strong> libcurl helpers</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../helpers/sharing.html"><strong aria-hidden="true">15.1.</strong> Share data between handles</a></li><li class="chapter-item "><a href="../../helpers/url/index.html"><strong aria-hidden="true">15.2.</strong> URL API</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../helpers/url/include.html"><strong aria-hidden="true">15.2.1.</strong> Include files</a></li><li class="chapter-item "><a href="../../helpers/url/init.html"><strong aria-hidden="true">15.2.2.</strong> Create, cleanup, duplicate</a></li><li class="chapter-item "><a href="../../helpers/url/parse.html"><strong aria-hidden="true">15.2.3.</strong> Parse a URL</a></li><li class="chapter-item "><a href="../../helpers/url/redirect.html"><strong aria-hidden="true">15.2.4.</strong> Redirect to URL</a></li><li class="chapter-item "><a href="../../helpers/url/get.html"><strong aria-hidden="true">15.2.5.</strong> Get a URL</a></li><li class="chapter-item "><a href="../../helpers/url/get-part.html"><strong aria-hidden="true">15.2.6.</strong> Get URL parts</a></li><li class="chapter-item "><a href="../../helpers/url/set-part.html"><strong aria-hidden="true">15.2.7.</strong> Set URL parts</a></li><li class="chapter-item "><a href="../../helpers/url/append-query.html"><strong aria-hidden="true">15.2.8.</strong> Append to the query</a></li><li class="chapter-item "><a href="../../helpers/url/setopt.html"><strong aria-hidden="true">15.2.9.</strong> CURLOPT_CURLU</a></li></ol></li><li class="chapter-item "><a href="../../helpers/ws/index.html"><strong aria-hidden="true">15.3.</strong> WebSocket</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../helpers/ws/support.html"><strong aria-hidden="true">15.3.1.</strong> Support</a></li><li class="chapter-item "><a href="../../helpers/ws/urls.html"><strong aria-hidden="true">15.3.2.</strong> URLs</a></li><li class="chapter-item "><a href="../../helpers/ws/concept.html"><strong aria-hidden="true">15.3.3.</strong> Concept</a></li><li class="chapter-item "><a href="../../helpers/ws/options.html"><strong aria-hidden="true">15.3.4.</strong> Options</a></li><li class="chapter-item "><a href="../../helpers/ws/read.html"><strong aria-hidden="true">15.3.5.</strong> Read</a></li><li class="chapter-item "><a href="../../helpers/ws/meta.html"><strong aria-hidden="true">15.3.6.</strong> Meta</a></li><li class="chapter-item "><a href="../../helpers/ws/write.html"><strong aria-hidden="true">15.3.7.</strong> Write</a></li></ol></li><li class="chapter-item "><a href="../../helpers/headerapi/index.html"><strong aria-hidden="true">15.4.</strong> Headers API</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../helpers/headerapi/struct.html"><strong aria-hidden="true">15.4.1.</strong> Header struct</a></li><li class="chapter-item "><a href="../../helpers/headerapi/get.html"><strong aria-hidden="true">15.4.2.</strong> Get a header</a></li><li class="chapter-item "><a href="../../helpers/headerapi/iterate.html"><strong aria-hidden="true">15.4.3.</strong> Iterate over headers</a></li></ol></li></ol></li><li class="chapter-item "><a href="../../examples/index.html"><strong aria-hidden="true">16.</strong> libcurl examples</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../examples/get.html"><strong aria-hidden="true">16.1.</strong> Get a simple HTTP page</a></li><li class="chapter-item "><a href="../../examples/getinmem.html"><strong aria-hidden="true">16.2.</strong> Get a response into memory</a></li><li class="chapter-item "><a href="../../examples/login.html"><strong aria-hidden="true">16.3.</strong> Submit a login form over HTTP</a></li><li class="chapter-item "><a href="../../examples/ftplist.html"><strong aria-hidden="true">16.4.</strong> Get an FTP directory listing</a></li><li class="chapter-item "><a href="../../examples/http-ul-nonblock.html"><strong aria-hidden="true">16.5.</strong> Non-blocking HTTP form-post</a></li></ol></li><li class="chapter-item "><a href="../../bindings/index.html"><strong aria-hidden="true">17.</strong> libcurl bindings</a></li><li class="chapter-item "><a href="../../internals/index.html"><strong aria-hidden="true">18.</strong> libcurl internals</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../internals/easy.html"><strong aria-hidden="true">18.1.</strong> Easy handles and connections</a></li><li class="chapter-item "><a href="../../internals/multi.html"><strong aria-hidden="true">18.2.</strong> Everything is multi</a></li><li class="chapter-item "><a href="../../internals/statemachines.html"><strong aria-hidden="true">18.3.</strong> State machines</a></li><li class="chapter-item "><a href="../../internals/handler.html"><strong aria-hidden="true">18.4.</strong> Protocol handler</a></li><li class="chapter-item "><a href="../../internals/backends.html"><strong aria-hidden="true">18.5.</strong> Backends</a></li><li class="chapter-item "><a href="../../internals/caches.html"><strong aria-hidden="true">18.6.</strong> Caches and state</a></li><li class="chapter-item "><a href="../../internals/timeouts.html"><strong aria-hidden="true">18.7.</strong> Timeouts</a></li><li class="chapter-item "><a href="../../internals/windows-vs-unix.html"><strong aria-hidden="true">18.8.</strong> Windows vs Unix</a></li><li class="chapter-item "><a href="../../internals/memory-debugging.html"><strong aria-hidden="true">18.9.</strong> Memory debugging</a></li><li class="chapter-item "><a href="../../internals/content-encoding.html"><strong aria-hidden="true">18.10.</strong> Content Encoding</a></li><li class="chapter-item "><a href="../../internals/structs.html"><strong aria-hidden="true">18.11.</strong> Structs</a></li><li class="chapter-item "><a href="../../internals/resolving.html"><strong aria-hidden="true">18.12.</strong> Resolving hostnames</a></li><li class="chapter-item "><a href="../../internals/tests/index.html"><strong aria-hidden="true">18.13.</strong> Tests</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../internals/tests/file-format.html"><strong aria-hidden="true">18.13.1.</strong> Test file format</a></li><li class="chapter-item "><a href="../../internals/tests/build.html"><strong aria-hidden="true">18.13.2.</strong> Build tests</a></li><li class="chapter-item "><a href="../../internals/tests/run.html"><strong aria-hidden="true">18.13.3.</strong> Run tests</a></li><li class="chapter-item "><a href="../../internals/tests/debug.html"><strong aria-hidden="true">18.13.4.</strong> Debug builds</a></li><li class="chapter-item "><a href="../../internals/tests/servers.html"><strong aria-hidden="true">18.13.5.</strong> Test servers</a></li><li class="chapter-item "><a href="../../internals/tests/curl.html"><strong aria-hidden="true">18.13.6.</strong> curl tests</a></li><li class="chapter-item "><a href="../../internals/tests/libcurl.html"><strong aria-hidden="true">18.13.7.</strong> libcurl tests</a></li><li class="chapter-item "><a href="../../internals/tests/unit.html"><strong aria-hidden="true">18.13.8.</strong> Unit tests</a></li><li class="chapter-item "><a href="../../internals/tests/valgrind.html"><strong aria-hidden="true">18.13.9.</strong> Valgrind</a></li><li class="chapter-item "><a href="../../internals/tests/ci.html"><strong aria-hidden="true">18.13.10.</strong> Continuous Integration</a></li><li class="chapter-item "><a href="../../internals/tests/autobuilds.html"><strong aria-hidden="true">18.13.11.</strong> Autobuilds</a></li><li class="chapter-item "><a href="../../internals/tests/torture.html"><strong aria-hidden="true">18.13.12.</strong> Torture</a></li></ol></li></ol></li><li class="chapter-item "><a href="../../bookindex.html"><strong aria-hidden="true">19.</strong> Index</a></li></ol> </div> <div id="sidebar-resize-handle" class="sidebar-resize-handle"> <div class="sidebar-resize-indicator"></div> </div> </nav>  <script> var sidebarScrollbox = document.querySelector('#sidebar .sidebar-scrollbox'); sidebarScrollbox.addEventListener('click', function(e) { if (e.target.tagName === 'A') { sessionStorage.setItem('sidebar-scroll', sidebarScrollbox.scrollTop); } }, { passive: true }); var sidebarScrollTop = sessionStorage.getItem('sidebar-scroll'); sessionStorage.removeItem('sidebar-scroll'); if (sidebarScrollTop) { // preserve sidebar scroll position when navigating via links within sidebar sidebarScrollbox.scrollTop = sidebarScrollTop; } else { // scroll sidebar to current active section when navigating via "next/previous chapter" buttons var activeSection = document.querySelector('#sidebar .active'); if (activeSection) { activeSection.scrollIntoView({ block: 'center' }); } } </script> <div id="page-wrapper" class="page-wrapper"> <div class="page"> <div id="menu-bar-hover-placeholder"></div> <div id="menu-bar" class="menu-bar sticky"> <div class="left-buttons"> <label id="sidebar-toggle" class="icon-button" for="sidebar-toggle-anchor" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar"> <i class="fa fa-bars"></i> </label> <button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list"> <i class="fa fa-paint-brush"></i> </button> <ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu"> <li role="none"><button role="menuitem" class="theme" id="light">Light</button></li> <li role="none"><button role="menuitem" class="theme" id="rust">Rust</button></li> <li role="none"><button role="menuitem" class="theme" id="coal">Coal</button></li> 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(Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar"> <i class="fa fa-search"></i> </button> </div> <h1 class="menu-title">everything curl</h1> <div class="right-buttons"> <a href="../../print.html" title="Print this book" aria-label="Print this book"> <i id="print-button" class="fa fa-print"></i> </a> </div> </div> <div id="search-wrapper" class="hidden"> <form id="searchbar-outer" class="searchbar-outer"> <input type="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header"> </form> <div id="searchresults-outer" class="searchresults-outer hidden"> <div id="searchresults-header" class="searchresults-header"></div> <ul id="searchresults"> </ul> </div> </div>  <script> document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible'); document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible'); Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) { link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1); }); </script> <div id="content" class="content"> <main> <h1 id="drive-with-multi"><a class="header" href="#drive-with-multi">Drive with multi</a></h1> <p>The name 'multi' is for multiple, as in multiple parallel transfers, all done in the same single thread. The multi API is non-blocking so it can also make sense to use it for single transfers.</p> <p>The transfer is still set in an "easy" <code>CURL *</code> handle as described <a href="../easyhandle.html">above</a>, but with the multi interface you also need a multi <code>CURLM *</code> handle created and use that to drive all the individual transfers. The multi handle can "hold" one or many easy handles:</p> <pre><code>CURLM *multi_handle = curl_multi_init(); </code></pre> <p>A multi handle can also get certain options set, which you do with <code>curl_multi_setopt()</code>, but in the simplest case you might not have anything to set there.</p> <p>To drive a multi interface transfer, you first need to add all the individual easy handles that should be transferred to the multi handle. You can add them to the multi handle at any point and you can remove them again whenever you like. Removing an easy handle from a multi handle removes the association and that particular transfer stops immediately.</p> <p>Adding an easy handle to the multi handle is easy:</p> <pre><code>curl_multi_add_handle( multi_handle, easy_handle ); </code></pre> <p>Removing one is just as easily done:</p> <pre><code>curl_multi_remove_handle( multi_handle, easy_handle ); </code></pre> <p>Having added the easy handles representing the transfers you want to perform, you write the transfer loop. With the multi interface, you do the looping so you can ask libcurl for a set of file descriptors and a timeout value and do the <code>select()</code> call yourself, or you can use the slightly simplified version which does that for us, with <code>curl_multi_wait</code>. The simplest loop could look like this: (<em>note that a real application would check return codes</em>)</p> <pre><code>int transfers_running; do { curl_multi_wait ( multi_handle, NULL, 0, 1000, NULL); curl_multi_perform ( multi_handle, &transfers_running ); } while (transfers_running); </code></pre> <p>The fourth argument to <code>curl_multi_wait</code>, set to 1000 in the example above, is a timeout in milliseconds. It is the longest time the function waits for any activity before it returns anyway. You do not want to lock up for too long before calling <code>curl_multi_perform</code> again as there are timeouts, progress callbacks and more that may lose precision if you do so.</p> <p>To instead do select() on our own, we extract the file descriptors and timeout value from libcurl like this (<em>note that a real application would check return codes</em>):</p> <pre><code>int transfers_running; do { fd_set fdread; fd_set fdwrite; fd_set fdexcep; int maxfd = -1; long timeout; /* extract timeout value */ curl_multi_timeout(multi_handle, &timeout); if (timeout < 0) timeout = 1000; /* convert to struct usable by select */ timeout.tv_sec = timeout / 1000; timeout.tv_usec = (timeout % 1000) * 1000; FD_ZERO(&fdread); FD_ZERO(&fdwrite); FD_ZERO(&fdexcep); /* get file descriptors from the transfers */ mc = curl_multi_fdset(multi_handle, &fdread, &fdwrite, &fdexcep, &maxfd); if (maxfd == -1) { SHORT_SLEEP; } else select(maxfd+1, &fdread, &fdwrite, &fdexcep, &timeout); /* timeout or readable/writable sockets */ curl_multi_perform(multi_handle, &transfers_running); } while ( transfers_running ); </code></pre> <p>Both these loops let you use one or more file descriptors of your own on which to wait, like if you read from your own sockets or a pipe or similar.</p> <p>Again: you can add and remove easy handles to the multi handle at any point during the looping. Removing a handle mid-transfer aborts that transfer.</p> <h2 id="when-is-a-single-transfer-done"><a class="header" href="#when-is-a-single-transfer-done">When is a single transfer done?</a></h2> <p>As the examples above show, a program can detect when an individual transfer completes by seeing that the <code>transfers_running</code> variable decreases.</p> <p>It can also call <code>curl_multi_info_read()</code>, which returns a pointer to a struct (a "message") if a transfer has ended and you can then find out the result of that transfer using that struct.</p> <p>When you do multiple parallel transfers, more than one transfer can of course complete in the same <code>curl_multi_perform</code> invocation and then you might need more than one call to <code>curl_multi_info_read</code> to get info about each completed transfer.</p> </main> <nav class="nav-wrapper" aria-label="Page navigation">  <a rel="prev" href="../../transfers/drive/easy.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left"> <i class="fa fa-angle-left"></i> </a> <a rel="next prefetch" href="../../transfers/drive/multi-socket.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right"> <i class="fa fa-angle-right"></i> </a> <div style="clear: both"></div> </nav> </div> </div> <nav class="nav-wide-wrapper" aria-label="Page navigation"> <a rel="prev" href="../../transfers/drive/easy.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left"> <i class="fa fa-angle-left"></i> </a> <a rel="next prefetch" href="../../transfers/drive/multi-socket.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right"> <i class="fa fa-angle-right"></i> </a> </nav> </div> <script> window.playground_copyable = true; </script> <script src="../../elasticlunr.min.js"></script> <script src="../../mark.min.js"></script> <script src="../../searcher.js"></script> <script src="../../clipboard.min.js"></script> <script src="../../highlight.js"></script> <script src="../../book.js"></script>  </div> </body> </html>