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+
+FAQ
+
+ 1. Philosophy
+  1.1 What is cURL?
+  1.2 What is libcurl?
+  1.3 What is curl not?
+  1.4 When will you make curl do XXXX ?
+  1.5 Who makes curl?
+  1.6 What do you get for making curl?
+  1.7 What about CURL from curl.com?
+  1.8 I have a problem, who do I mail?
+  1.9 Where do I buy commercial support for curl?
+  1.10 How many are using curl?
+  1.11 Why do you not update ca-bundle.crt
+  1.12 I have a problem, who can I chat with?
+  1.13 curl's ECCN number?
+  1.14 How do I submit my patch?
+  1.15 How do I port libcurl to my OS?
+
+ 2. Install Related Problems
+  2.1 configure fails when using static libraries
+  2.2 Does curl work/build with other SSL libraries?
+  2.4 Does curl support SOCKS (RFC 1928) ?
+
+ 3. Usage Problems
+  3.1 curl: (1) SSL is disabled, https: not supported
+  3.2 How do I tell curl to resume a transfer?
+  3.3 Why does my posting using -F not work?
+  3.4 How do I tell curl to run custom FTP commands?
+  3.5 How can I disable the Accept: */* header?
+  3.6 Does curl support ASP, XML, XHTML or HTML version Y?
+  3.7 Can I use curl to delete/rename a file through FTP?
+  3.8 How do I tell curl to follow HTTP redirects?
+  3.9 How do I use curl in my favorite programming language?
+  3.10 What about SOAP, WebDAV, XML-RPC or similar protocols over HTTP?
+  3.11 How do I POST with a different Content-Type?
+  3.12 Why do FTP-specific features over HTTP proxy fail?
+  3.13 Why do my single/double quotes fail?
+  3.14 Does curl support JavaScript or PAC (automated proxy config)?
+  3.15 Can I do recursive fetches with curl?
+  3.16 What certificates do I need when I use SSL?
+  3.17 How do I list the root directory of an FTP server?
+  3.18 Can I use curl to send a POST/PUT and not wait for a response?
+  3.19 How do I get HTTP from a host using a specific IP address?
+  3.20 How to SFTP from my user's home directory?
+  3.21 Protocol xxx not supported or disabled in libcurl
+  3.22 curl -X gives me HTTP problems
+
+ 4. Running Problems
+  4.2 Why do I get problems when I use & or % in the URL?
+  4.3 How can I use {, }, [ or ] to specify multiple URLs?
+  4.4 Why do I get downloaded data even though the web page does not exist?
+  4.5 Why do I get return code XXX from an HTTP server?
+   4.5.1 "400 Bad Request"
+   4.5.2 "401 Unauthorized"
+   4.5.3 "403 Forbidden"
+   4.5.4 "404 Not Found"
+   4.5.5 "405 Method Not Allowed"
+   4.5.6 "301 Moved Permanently"
+  4.6 Can you tell me what error code 142 means?
+  4.7 How do I keep user names and passwords secret in curl command lines?
+  4.8 I found a bug
+  4.9 curl cannot authenticate to a server that requires NTLM?
+  4.10 My HTTP request using HEAD, PUT or DELETE does not work
+  4.11 Why do my HTTP range requests return the full document?
+  4.12 Why do I get "certificate verify failed" ?
+  4.13 Why is curl -R on Windows one hour off?
+  4.14 Redirects work in browser but not with curl
+  4.15 FTPS does not work
+  4.16 My HTTP POST or PUT requests are slow
+  4.17 Non-functional connect timeouts on Windows
+  4.18 file:// URLs containing drive letters (Windows, NetWare)
+  4.19 Why does not curl return an error when the network cable is unplugged?
+  4.20 curl does not return error for HTTP non-200 responses
+
+ 5. libcurl Issues
+  5.1 Is libcurl thread-safe?
+  5.2 How can I receive all data into a large memory chunk?
+  5.3 How do I fetch multiple files with libcurl?
+  5.4 Does libcurl do Winsock initialization on win32 systems?
+  5.5 Does CURLOPT_WRITEDATA and CURLOPT_READDATA work on win32 ?
+  5.6 What about Keep-Alive or persistent connections?
+  5.7 Link errors when building libcurl on Windows
+  5.8 libcurl.so.X: open failed: No such file or directory
+  5.9 How does libcurl resolve host names?
+  5.10 How do I prevent libcurl from writing the response to stdout?
+  5.11 How do I make libcurl not receive the whole HTTP response?
+  5.12 Can I make libcurl fake or hide my real IP address?
+  5.13 How do I stop an ongoing transfer?
+  5.14 Using C++ non-static functions for callbacks?
+  5.15 How do I get an FTP directory listing?
+  5.16 I want a different time-out
+  5.17 Can I write a server with libcurl?
+  5.18 Does libcurl use threads?
+
+ 6. License Issues
+  6.1 I have a GPL program, can I use the libcurl library?
+  6.2 I have a closed-source program, can I use the libcurl library?
+  6.3 I have a BSD licensed program, can I use the libcurl library?
+  6.4 I have a program that uses LGPL libraries, can I use libcurl?
+  6.5 Can I modify curl/libcurl for my program and keep the changes secret?
+  6.6 Can you please change the curl/libcurl license to XXXX?
+  6.7 What are my obligations when using libcurl in my commercial apps?
+
+ 7. PHP/CURL Issues
+  7.1 What is PHP/CURL?
+  7.2 Who wrote PHP/CURL?
+  7.3 Can I perform multiple requests using the same handle?
+  7.4 Does PHP/CURL have dependencies?
+
+ 8. Development
+  8.1 Why does curl use C89?
+  8.2 Will curl be rewritten?
+
+==============================================================================
+
+1. Philosophy
+
+  1.1 What is cURL?
+
+  cURL is the name of the project. The name is a play on 'Client for URLs',
+  originally with URL spelled in uppercase to make it obvious it deals with
+  URLs. The fact it can also be read as 'see URL' also helped, it works as
+  an abbreviation for "Client URL Request Library" or why not the recursive
+  version: "curl URL Request Library".
+
+  The cURL project produces two products:
+
+  libcurl
+
+    A client-side URL transfer library, supporting DICT, FILE, FTP, FTPS,
+    GOPHER, GOPHERS, HTTP, HTTPS, IMAP, IMAPS, LDAP, LDAPS, MQTT, POP3, POP3S,
+    RTMP, RTMPS, RTSP, SCP, SFTP, SMB, SMBS, SMTP, SMTPS, TELNET, TFTP, WS
+    and WSS.
+
+    libcurl supports HTTPS certificates, HTTP POST, HTTP PUT, FTP uploading,
+    Kerberos, SPNEGO, HTTP form based upload, proxies, cookies, user+password
+    authentication, file transfer resume, http proxy tunneling and more.
+
+    libcurl is highly portable, it builds and works identically on numerous
+    platforms, including Solaris, NetBSD, FreeBSD, OpenBSD, Darwin, HP-UX,
+    IRIX, AIX, Tru64, Linux, UnixWare, HURD, Windows, Amiga, OS/2, macOS,
+    Ultrix, QNX, OpenVMS, RISC OS, Novell NetWare, DOS, Symbian, OSF, Android,
+    Minix, IBM TPF and more...
+
+    libcurl is free, thread-safe, IPv6 compatible, feature rich, well
+    supported and fast.
+
+  curl
+
+    A command line tool for getting or sending data using URL syntax.
+
+    Since curl uses libcurl, curl supports the same wide range of common
+    Internet protocols that libcurl does.
+
+  We pronounce curl with an initial k sound. It rhymes with words like girl
+  and earl. This is a short WAV file to help you:
+
+     https://media.merriam-webster.com/soundc11/c/curl0001.wav
+
+  There are numerous sub-projects and related projects that also use the word
+  curl in the project names in various combinations, but you should take
+  notice that this FAQ is directed at the command-line tool named curl (and
+  libcurl the library), and may therefore not be valid for other curl-related
+  projects. (There is however a small section for the PHP/CURL in this FAQ.)
+
+  1.2 What is libcurl?
+
+  libcurl is a reliable and portable library for doing Internet data transfers
+  using one or more of its supported Internet protocols.
+
+  You can use libcurl freely in your application, be it open source,
+  commercial or closed-source.
+
+  libcurl is most probably the most portable, most powerful and most often
+  used C-based multi-platform file transfer library on this planet - be it
+  open source or commercial.
+
+  1.3 What is curl not?
+
+  curl is not a wget clone. That is a common misconception. Never, during
+  curl's development, have we intended curl to replace wget or compete on its
+  market. curl is targeted at single-shot file transfers.
+
+  curl is not a website mirroring program. If you want to use curl to mirror
+  something: fine, go ahead and write a script that wraps around curl or use
+  libcurl to make it reality.
+
+  curl is not an FTP site mirroring program. Sure, get and send FTP with curl
+  but if you want systematic and sequential behavior you should write a
+  script (or write a new program that interfaces libcurl) and do it.
+
+  curl is not a PHP tool, even though it works perfectly well when used from
+  or with PHP (when using the PHP/CURL module).
+
+  curl is not a program for a single operating system. curl exists, compiles,
+  builds and runs under a wide range of operating systems, including all
+  modern Unixes (and a bunch of older ones too), Windows, Amiga, OS/2, macOS,
+  QNX etc.
+
+  1.4 When will you make curl do XXXX ?
+
+  We love suggestions of what to change in order to make curl and libcurl
+  better. We do however believe in a few rules when it comes to the future of
+  curl:
+
+  curl -- the command line tool -- is to remain a non-graphical command line
+  tool. If you want GUIs or fancy scripting capabilities, you should look for
+  another tool that uses libcurl.
+
+  We do not add things to curl that other small and available tools already do
+  well at the side. curl's output can be piped into another program or
+  redirected to another file for the next program to interpret.
+
+  We focus on protocol related issues and improvements. If you want to do more
+  magic with the supported protocols than curl currently does, chances are
+  good we will agree. If you want to add more protocols, we may agree.
+
+  If you want someone else to do all the work while you wait for us to
+  implement it for you, that is not a friendly attitude. We spend a
+  considerable time already on maintaining and developing curl. In order to
+  get more out of us, you should consider trading in some of your time and
+  effort in return. Simply go to the GitHub repository which resides at
+  https://github.com/curl/curl, fork the project, and create pull requests
+  with your proposed changes.
+
+  If you write the code, chances are better that it will get into curl faster.
+
+  1.5 Who makes curl?
+
+  curl and libcurl are not made by any single individual. Daniel Stenberg is
+  project leader and main developer, but other persons' submissions are
+  important and crucial. Anyone can contribute and post their changes and
+  improvements and have them inserted in the main sources (of course on the
+  condition that developers agree that the fixes are good).
+
+  The full list of all contributors is found in the docs/THANKS file.
+
+  curl is developed by a community, with Daniel at the wheel.
+
+  1.6 What do you get for making curl?
+
+  Project cURL is entirely free and open. We do this voluntarily, mostly in
+  our spare time. Companies may pay individual developers to work on curl.
+  This is not controlled by nor supervised in any way by the curl project.
+
+  We get help from companies. Haxx provides website, bandwidth, mailing lists
+  etc, GitHub hosts the primary git repository and other services like the bug
+  tracker at https://github.com/curl/curl. Also again, some companies have
+  sponsored certain parts of the development in the past and I hope some will
+  continue to do so in the future.
+
+  If you want to support our project, consider a donation or a banner-program
+  or even better: by helping us with coding, documenting or testing etc.
+
+  See also: https://curl.se/sponsors.html
+
+  1.7 What about CURL from curl.com?
+
+  During the summer of 2001, curl.com was busy advertising their client-side
+  programming language for the web, named CURL.
+
+  We are in no way associated with curl.com or their CURL programming
+  language.
+
+  Our project name curl has been in effective use since 1998. We were not the
+  first computer related project to use the name "curl" and do not claim any
+  rights to the name.
+
+  We recognize that we will be living in parallel with curl.com and wish them
+  every success.
+
+  1.8 I have a problem, who do I mail?
+
+  Please do not mail any single individual unless you really need to. Keep
+  curl-related questions on a suitable mailing list. All available mailing
+  lists are listed in the MANUAL document and online at
+  https://curl.se/mail/
+
+  Keeping curl-related questions and discussions on mailing lists allows
+  others to join in and help, to share their ideas, to contribute their
+  suggestions and to spread their wisdom. Keeping discussions on public mailing
+  lists also allows for others to learn from this (both current and future
+  users thanks to the web based archives of the mailing lists), thus saving us
+  from having to repeat ourselves even more. Thanks for respecting this.
+
+  If you have found or simply suspect a security problem in curl or libcurl,
+  submit all the details at https://hackerone.one/curl. On there we keep the
+  issue private while we investigate, confirm it, work and validate a fix and
+  agree on a time schedule for publication etc. That way we produce a fix in a
+  timely manner before the flaw is announced to the world, reducing the impact
+  the problem risks having on existing users.
+
+  Security issues can also be taking to the curl security team by emailing
+  security at curl.se (closed list of receivers, mails are not disclosed).
+
+  1.9 Where do I buy commercial support for curl?
+
+  curl is fully open source. It means you can hire any skilled engineer to fix
+  your curl-related problems.
+
+  We list available alternatives on the curl website:
+  https://curl.se/support.html
+
+  1.10 How many are using curl?
+
+  It is impossible to tell.
+
+  We do not know how many users that knowingly have installed and use curl.
+
+  We do not know how many users that use curl without knowing that they are in
+  fact using it.
+
+  We do not know how many users that downloaded or installed curl and then
+  never use it.
+
+  In 2020, we estimate that curl runs in roughly ten billion installations
+  world wide.
+
+  1.11 Why do you not update ca-bundle.crt
+
+  In the cURL project we have decided not to attempt to keep this file updated
+  (or even present) since deciding what to add to a ca cert bundle is an
+  undertaking we have not been ready to accept, and the one we can get from
+  Mozilla is perfectly fine so there is no need to duplicate that work.
+
+  Today, with many services performed over HTTPS, every operating system
+  should come with a default ca cert bundle that can be deemed somewhat
+  trustworthy and that collection (if reasonably updated) should be deemed to
+  be a lot better than a private curl version.
+
+  If you want the most recent collection of ca certs that Mozilla Firefox
+  uses, we recommend that you extract the collection yourself from Mozilla
+  Firefox (by running 'make ca-bundle), or by using our online service setup
+  for this purpose: https://curl.se/docs/caextract.html
+
+  1.12 I have a problem who, can I chat with?
+
+  There is a bunch of friendly people hanging out in the #curl channel on the
+  IRC network libera.chat. If you are polite and nice, chances are good that
+  you can get -- or provide -- help instantly.
+
+  1.13 curl's ECCN number?
+
+  The US government restricts exports of software that contains or uses
+  cryptography. When doing so, the Export Control Classification Number (ECCN)
+  is used to identify the level of export control etc.
+
+  Apache Software Foundation gives a good explanation of ECCNs at
+  https://www.apache.org/dev/crypto.html
+
+  We believe curl's number might be ECCN 5D002, another possibility is
+  5D992. It seems necessary to write them (the authority that administers ECCN
+  numbers), asking to confirm.
+
+  Comprehensible explanations of the meaning of such numbers and how to obtain
+  them (resp.) are here
+
+  https://www.bis.doc.gov/licensing/exportingbasics.htm
+  https://www.bis.doc.gov/licensing/do_i_needaneccn.html
+
+  An incomprehensible description of the two numbers above is here
+  https://www.bis.doc.gov/index.php/documents/new-encryption/1653-ccl5-pt2-3
+
+  1.14 How do I submit my patch?
+
+  We strongly encourage you to submit changes and improvements directly as
+  "pull requests" on GitHub: https://github.com/curl/curl/pulls
+
+  If you for any reason cannot or will not deal with GitHub, send your patch to
+  the curl-library mailing list. We are many subscribers there and there are
+  lots of people who can review patches, comment on them and "receive" them
+  properly.
+
+  Lots of more details are found in the CONTRIBUTE.md and INTERNALS.md
+  documents.
+
+  1.15 How do I port libcurl to my OS?
+
+  Here's a rough step-by-step:
+
+  1. copy a suitable lib/config-*.h file as a start to lib/config-[youros].h
+
+  2. edit lib/config-[youros].h to match your OS and setup
+
+  3. edit lib/curl_setup.h to include config-[youros].h when your OS is
+     detected by the preprocessor, in the style others already exist
+
+  4. compile lib/*.c and make them into a library
+
+
+2. Install Related Problems
+
+  2.1 configure fails when using static libraries
+
+  You may find that configure fails to properly detect the entire dependency
+  chain of libraries when you provide static versions of the libraries that
+  configure checks for.
+
+  The reason why static libraries is much harder to deal with is that for them
+  we do not get any help but the script itself must know or check what more
+  libraries that are needed (with shared libraries, that dependency "chain" is
+  handled automatically). This is a error-prone process and one that also
+  tends to vary over time depending on the release versions of the involved
+  components and may also differ between operating systems.
+
+  For that reason, configure does few attempts to actually figure this out and
+  you are instead encouraged to set LIBS and LDFLAGS accordingly when you
+  invoke configure, and point out the needed libraries and set the necessary
+  flags yourself.
+
+  2.2 Does curl work with other SSL libraries?
+
+  curl has been written to use a generic SSL function layer internally, and
+  that SSL functionality can then be provided by one out of many different SSL
+  backends.
+
+  curl can be built to use one of the following SSL alternatives: OpenSSL,
+  libressl, BoringSSL, GnuTLS, wolfSSL, NSS, mbedTLS, Secure
+  Transport (native iOS/OS X), Schannel (native Windows), GSKit (native IBM
+  i), BearSSL, or Rustls. They all have their pros and cons, and we try to
+  maintain a comparison of them here: https://curl.se/docs/ssl-compared.html
+
+  2.4 Does curl support SOCKS (RFC 1928) ?
+
+  Yes, SOCKS 4 and 5 are supported.
+
+3. Usage problems
+
+  3.1 curl: (1) SSL is disabled, https: not supported
+
+  If you get this output when trying to get anything from an https:// server,
+  it means that the instance of curl/libcurl that you are using was built
+  without support for this protocol.
+
+  This could have happened if the configure script that was run at build time
+  could not find all libs and include files curl requires for SSL to work. If
+  the configure script fails to find them, curl is simply built without SSL
+  support.
+
+  To get the https:// support into a curl that was previously built but that
+  reports that https:// is not supported, you should dig through the document
+  and logs and check out why the configure script does not find the SSL libs
+  and/or include files.
+
+  Also, check out the other paragraph in this FAQ labeled "configure does not
+  find OpenSSL even when it is installed".
+
+  3.2 How do I tell curl to resume a transfer?
+
+  curl supports resumed transfers both ways on both FTP and HTTP.
+  Try the -C option.
+
+  3.3 Why does my posting using -F not work?
+
+  You cannot arbitrarily use -F or -d, the choice between -F or -d depends on
+  the HTTP operation you need curl to do and what the web server that will
+  receive your post expects.
+
+  If the form you are trying to submit uses the type 'multipart/form-data',
+  then and only then you must use the -F type. In all the most common cases,
+  you should use -d which then causes a posting with the type
+  'application/x-www-form-urlencoded'.
+
+  This is described in some detail in the MANUAL and TheArtOfHttpScripting
+  documents, and if you do not understand it the first time, read it again
+  before you post questions about this to the mailing list. Also, try reading
+  through the mailing list archives for old postings and questions regarding
+  this.
+
+  3.4 How do I tell curl to run custom FTP commands?
+
+  You can tell curl to perform optional commands both before and/or after a
+  file transfer. Study the -Q/--quote option.
+
+  Since curl is used for file transfers, you do not normally use curl to
+  perform FTP commands without transferring anything. Therefore you must
+  always specify a URL to transfer to/from even when doing custom FTP
+  commands, or use -I which implies the "no body" option sent to libcurl.
+
+  3.5 How can I disable the Accept: */* header?
+
+  You can change all internally generated headers by adding a replacement with
+  the -H/--header option. By adding a header with empty contents you safely
+  disable that one. Use -H "Accept:" to disable that specific header.
+
+  3.6 Does curl support ASP, XML, XHTML or HTML version Y?
+
+  To curl, all contents are alike. It does not matter how the page was
+  generated. It may be ASP, PHP, Perl, shell-script, SSI or plain HTML
+  files. There is no difference to curl and it does not even know what kind of
+  language that generated the page.
+
+  See also item 3.14 regarding JavaScript.
+
+  3.7 Can I use curl to delete/rename a file through FTP?
+
+  Yes. You specify custom FTP commands with -Q/--quote.
+
+  One example would be to delete a file after you have downloaded it:
+
+     curl -O ftp://download.com/coolfile -Q '-DELE coolfile'
+
+  or rename a file after upload:
+
+     curl -T infile ftp://upload.com/dir/ -Q "-RNFR infile" -Q "-RNTO newname"
+
+  3.8 How do I tell curl to follow HTTP redirects?
+
+  curl does not follow so-called redirects by default. The Location: header
+  that informs the client about this is only interpreted if you are using the
+  -L/--location option. As in:
+
+     curl -L http://redirector.com
+
+  Not all redirects are HTTP ones, see 4.14
+
+  3.9 How do I use curl in my favorite programming language?
+
+  Many programming languages have interfaces/bindings that allow you to use
+  curl without having to use the command line tool. If you are fluent in such
+  a language, you may prefer to use one of these interfaces instead.
+
+  Find out more about which languages that support curl directly, and how to
+  install and use them, in the libcurl section of the curl website:
+  https://curl.se/libcurl/
+
+  All the various bindings to libcurl are made by other projects and people,
+  outside of the cURL project. The cURL project itself only produces libcurl
+  with its plain C API. If you do not find anywhere else to ask you can ask
+  about bindings on the curl-library list too, but be prepared that people on
+  that list may not know anything about bindings.
+
+  In December 2021, there were interfaces available for the following
+  languages: Ada95, Basic, C, C++, Ch, Cocoa, D, Delphi, Dylan, Eiffel,
+  Euphoria, Falcon, Ferite, Gambas, glib/GTK+, Go, Guile, Harbour, Haskell,
+  Java, Julia, Lisp, Lua, Mono, .NET, node.js, Object-Pascal, OCaml, Pascal,
+  Perl, PHP, PostgreSQL, Python, R, Rexx, Ring, RPG, Ruby, Rust, Scheme,
+  Scilab, S-Lang, Smalltalk, SP-Forth, SPL, Tcl, Visual Basic, Visual FoxPro,
+  Q, wxwidgets, XBLite and Xoho. By the time you read this, additional ones
+  may have appeared.
+
+  3.10 What about SOAP, WebDAV, XML-RPC or similar protocols over HTTP?
+
+  curl adheres to the HTTP spec, which basically means you can play with *any*
+  protocol that is built on top of HTTP. Protocols such as SOAP, WEBDAV and
+  XML-RPC are all such ones. You can use -X to set custom requests and -H to
+  set custom headers (or replace internally generated ones).
+
+  Using libcurl is of course just as good and you would just use the proper
+  library options to do the same.
+
+  3.11 How do I POST with a different Content-Type?
+
+  You can always replace the internally generated headers with -H/--header.
+  To make a simple HTTP POST with text/xml as content-type, do something like:
+
+        curl -d "datatopost" -H "Content-Type: text/xml" [URL]
+
+  3.12 Why do FTP-specific features over HTTP proxy fail?
+
+  Because when you use an HTTP proxy, the protocol spoken on the network will
+  be HTTP, even if you specify an FTP URL. This effectively means that you
+  normally cannot use FTP-specific features such as FTP upload and FTP quote
+  etc.
+
+  There is one exception to this rule, and that is if you can "tunnel through"
+  the given HTTP proxy. Proxy tunneling is enabled with a special option (-p)
+  and is generally not available as proxy admins usually disable tunneling to
+  ports other than 443 (which is used for HTTPS access through proxies).
+
+  3.13 Why do my single/double quotes fail?
+
+  To specify a command line option that includes spaces, you might need to
+  put the entire option within quotes. Like in:
+
+   curl -d " with spaces " url.com
+
+  or perhaps
+
+   curl -d ' with spaces ' url.com
+
+  Exactly what kind of quotes and how to do this is entirely up to the shell
+  or command line interpreter that you are using. For most unix shells, you
+  can more or less pick either single (') or double (") quotes. For
+  Windows/DOS command prompts you must use double (") quotes, and if the
+  option string contains inner double quotes you can escape them with a
+  backslash.
+
+  For Windows powershell the arguments are not always passed on as expected
+  because curl is not a powershell script. You may or may not be able to use
+  single quotes. To escape inner double quotes seems to require a
+  backslash-backtick escape sequence and the outer quotes as double quotes.
+
+  Please study the documentation for your particular environment. Examples in
+  the curl docs will use a mix of both of these as shown above. You must
+  adjust them to work in your environment.
+
+  Remember that curl works and runs on more operating systems than most single
+  individuals have ever tried.
+
+  3.14 Does curl support JavaScript or PAC (automated proxy config)?
+
+  Many web pages do magic stuff using embedded JavaScript. curl and libcurl
+  have no built-in support for that, so it will be treated just like any other
+  contents.
+
+  .pac files are a Netscape invention and are sometimes used by organizations
+  to allow them to differentiate which proxies to use. The .pac contents is
+  just a JavaScript program that gets invoked by the browser and that returns
+  the name of the proxy to connect to. Since curl does not support JavaScript,
+  it cannot support .pac proxy configuration either.
+
+  Some workarounds usually suggested to overcome this JavaScript dependency:
+
+  Depending on the JavaScript complexity, write up a script that translates it
+  to another language and execute that.
+
+  Read the JavaScript code and rewrite the same logic in another language.
+
+  Implement a JavaScript interpreter, people have successfully used the
+  Mozilla JavaScript engine in the past.
+
+  Ask your admins to stop this, for a static proxy setup or similar.
+
+  3.15 Can I do recursive fetches with curl?
+
+  No. curl itself has no code that performs recursive operations, such as
+  those performed by wget and similar tools.
+
+  There exists wrapper scripts with that functionality (for example the
+  curlmirror perl script), and you can write programs based on libcurl to do
+  it, but the command line tool curl itself cannot.
+
+  3.16 What certificates do I need when I use SSL?
+
+  There are three different kinds of "certificates" to keep track of when we
+  talk about using SSL-based protocols (HTTPS or FTPS) using curl or libcurl.
+
+  CLIENT CERTIFICATE
+
+  The server you communicate with may require that you can provide this in
+  order to prove that you actually are who you claim to be. If the server
+  does not require this, you do not need a client certificate.
+
+  A client certificate is always used together with a private key, and the
+  private key has a pass phrase that protects it.
+
+  SERVER CERTIFICATE
+
+  The server you communicate with has a server certificate. You can and should
+  verify this certificate to make sure that you are truly talking to the real
+  server and not a server impersonating it.
+
+  CERTIFICATE AUTHORITY CERTIFICATE ("CA cert")
+
+  You often have several CA certs in a CA cert bundle that can be used to
+  verify a server certificate that was signed by one of the authorities in the
+  bundle. curl does not come with a CA cert bundle but most curl installs
+  provide one. You can also override the default.
+
+  The server certificate verification process is made by using a Certificate
+  Authority certificate ("CA cert") that was used to sign the server
+  certificate. Server certificate verification is enabled by default in curl
+  and libcurl and is often the reason for problems as explained in FAQ entry
+  4.12 and the SSLCERTS document
+  (https://curl.se/docs/sslcerts.html). Server certificates that are
+  "self-signed" or otherwise signed by a CA that you do not have a CA cert
+  for, cannot be verified. If the verification during a connect fails, you are
+  refused access. You then need to explicitly disable the verification to
+  connect to the server.
+
+  3.17 How do I list the root directory of an FTP server?
+
+  There are two ways. The way defined in the RFC is to use an encoded slash
+  in the first path part. List the "/tmp" directory like this:
+
+     curl ftp://ftp.sunet.se/%2ftmp/
+
+  or the not-quite-kosher-but-more-readable way, by simply starting the path
+  section of the URL with a slash:
+
+     curl ftp://ftp.sunet.se//tmp/
+
+  3.18 Can I use curl to send a POST/PUT and not wait for a response?
+
+  No.
+
+  You can easily write your own program using libcurl to do such stunts.
+
+  3.19 How do I get HTTP from a host using a specific IP address?
+
+  For example, you may be trying out a website installation that is not yet in
+  the DNS. Or you have a site using multiple IP addresses for a given host
+  name and you want to address a specific one out of the set.
+
+  Set a custom Host: header that identifies the server name you want to reach
+  but use the target IP address in the URL:
+
+    curl --header "Host: www.example.com" http://127.0.0.1/
+
+  You can also opt to add faked host name entries to curl with the --resolve
+  option. That has the added benefit that things like redirects will also work
+  properly. The above operation would instead be done as:
+
+    curl --resolve www.example.com:80:127.0.0.1 http://www.example.com/
+
+  3.20 How to SFTP from my user's home directory?
+
+  Contrary to how FTP works, SFTP and SCP URLs specify the exact directory to
+  work with. It means that if you do not specify that you want the user's home
+  directory, you get the actual root directory.
+
+  To specify a file in your user's home directory, you need to use the correct
+  URL syntax which for SFTP might look similar to:
+
+    curl -O -u user:password sftp://example.com/~/file.txt
+
+  and for SCP it is just a different protocol prefix:
+
+    curl -O -u user:password scp://example.com/~/file.txt
+
+  3.21 Protocol xxx not supported or disabled in libcurl
+
+  When passing on a URL to curl to use, it may respond that the particular
+  protocol is not supported or disabled. The particular way this error message
+  is phrased is because curl does not make a distinction internally of whether
+  a particular protocol is not supported (i.e. never got any code added that
+  knows how to speak that protocol) or if it was explicitly disabled. curl can
+  be built to only support a given set of protocols, and the rest would then
+  be disabled or not supported.
+
+  Note that this error will also occur if you pass a wrongly spelled protocol
+  part as in "htpt://example.com" or as in the less evident case if you prefix
+  the protocol part with a space as in " http://example.com/".
+
+  3.22 curl -X gives me HTTP problems
+
+  In normal circumstances, -X should hardly ever be used.
+
+  By default you use curl without explicitly saying which request method to
+  use when the URL identifies an HTTP transfer. If you just pass in a URL like
+  "curl http://example.com" it will use GET. If you use -d or -F curl will use
+  POST, -I will cause a HEAD and -T will make it a PUT.
+
+  If for whatever reason you are not happy with these default choices that curl
+  does for you, you can override those request methods by specifying -X
+  [WHATEVER]. This way you can for example send a DELETE by doing "curl -X
+  DELETE [URL]".
+
+  It is thus pointless to do "curl -XGET [URL]" as GET would be used
+  anyway. In the same vein it is pointless to do "curl -X POST -d data
+  [URL]"... But you can make a fun and somewhat rare request that sends a
+  request-body in a GET request with something like "curl -X GET -d data
+  [URL]"
+
+  Note that -X does not actually change curl's behavior as it only modifies the
+  actual string sent in the request, but that may of course trigger a
+  different set of events.
+
+  Accordingly, by using -XPOST on a command line that for example would follow
+  a 303 redirect, you will effectively prevent curl from behaving
+  correctly. Be aware.
+
+
+4. Running Problems
+
+  4.2 Why do I get problems when I use & or % in the URL?
+
+  In general Unix shells, the & symbol is treated specially and when used, it
+  runs the specified command in the background. To safely send the & as a part
+  of a URL, you should quote the entire URL by using single (') or double (")
+  quotes around it. Similar problems can also occur on some shells with other
+  characters, including ?*!$~(){}<>\|;`. When in doubt, quote the URL.
+
+  An example that would invoke a remote CGI that uses &-symbols could be:
+
+     curl 'http://www.altavista.com/cgi-bin/query?text=yes&q=curl'
+
+  In Windows, the standard DOS shell treats the percent sign specially and you
+  need to use TWO percent signs for each single one you want to use in the
+  URL.
+
+  If you want a literal percent sign to be part of the data you pass in a POST
+  using -d/--data you must encode it as '%25' (which then also needs the
+  percent sign doubled on Windows machines).
+
+  4.3 How can I use {, }, [ or ] to specify multiple URLs?
+
+  Because those letters have a special meaning to the shell, to be used in
+  a URL specified to curl you must quote them.
+
+  An example that downloads two URLs (sequentially) would be:
+
+    curl '{curl,www}.haxx.se'
+
+  To be able to use those characters as actual parts of the URL (without using
+  them for the curl URL "globbing" system), use the -g/--globoff option:
+
+    curl -g 'www.site.com/weirdname[].html'
+
+  4.4 Why do I get downloaded data even though the web page does not exist?
+
+  curl asks remote servers for the page you specify. If the page does not exist
+  at the server, the HTTP protocol defines how the server should respond and
+  that means that headers and a "page" will be returned. That is simply how
+  HTTP works.
+
+  By using the --fail option you can tell curl explicitly to not get any data
+  if the HTTP return code does not say success.
+
+  4.5 Why do I get return code XXX from an HTTP server?
+
+  RFC2616 clearly explains the return codes. This is a short transcript. Go
+  read the RFC for exact details:
+
+    4.5.1 "400 Bad Request"
+
+    The request could not be understood by the server due to malformed
+    syntax. The client SHOULD NOT repeat the request without modifications.
+
+    4.5.2 "401 Unauthorized"
+
+    The request requires user authentication.
+
+    4.5.3 "403 Forbidden"
+
+    The server understood the request, but is refusing to fulfill it.
+    Authorization will not help and the request SHOULD NOT be repeated.
+
+    4.5.4 "404 Not Found"
+
+    The server has not found anything matching the Request-URI. No indication
+    is given as to whether the condition is temporary or permanent.
+
+    4.5.5 "405 Method Not Allowed"
+
+    The method specified in the Request-Line is not allowed for the resource
+    identified by the Request-URI. The response MUST include an Allow header
+    containing a list of valid methods for the requested resource.
+
+    4.5.6 "301 Moved Permanently"
+
+    If you get this return code and an HTML output similar to this:
+
+       <H1>Moved Permanently</H1> The document has moved <A
+       HREF="http://same_url_now_with_a_trailing_slash/">here</A>.
+
+    it might be because you requested a directory URL but without the trailing
+    slash. Try the same operation again _with_ the trailing URL, or use the
+    -L/--location option to follow the redirection.
+
+  4.6 Can you tell me what error code 142 means?
+
+  All curl error codes are described at the end of the man page, in the
+  section called "EXIT CODES".
+
+  Error codes that are larger than the highest documented error code means
+  that curl has exited due to a crash. This is a serious error, and we
+  appreciate a detailed bug report from you that describes how we could go
+  ahead and repeat this.
+
+  4.7 How do I keep user names and passwords secret in curl command lines?
+
+  This problem has two sides:
+
+  The first part is to avoid having clear-text passwords in the command line
+  so that they do not appear in 'ps' outputs and similar. That is easily
+  avoided by using the "-K" option to tell curl to read parameters from a file
+  or stdin to which you can pass the secret info. curl itself will also
+  attempt to "hide" the given password by blanking out the option - this
+  does not work on all platforms.
+
+  To keep the passwords in your account secret from the rest of the world is
+  not a task that curl addresses. You could of course encrypt them somehow to
+  at least hide them from being read by human eyes, but that is not what
+  anyone would call security.
+
+  Also note that regular HTTP (using Basic authentication) and FTP passwords
+  are sent as cleartext across the network. All it takes for anyone to fetch
+  them is to listen on the network. Eavesdropping is easy. Use more secure
+  authentication methods (like Digest, Negotiate or even NTLM) or consider the
+  SSL-based alternatives HTTPS and FTPS.
+
+  4.8 I found a bug
+
+  It is not a bug if the behavior is documented. Read the docs first.
+  Especially check out the KNOWN_BUGS file, it may be a documented bug.
+
+  If it is a problem with a binary you have downloaded or a package for your
+  particular platform, try contacting the person who built the package/archive
+  you have.
+
+  If there is a bug, read the BUGS document first. Then report it as described
+  in there.
+
+  4.9 curl cannot authenticate to a server that requires NTLM?
+
+  NTLM support requires OpenSSL, GnuTLS, mbedTLS, NSS, Secure Transport, or
+  Microsoft Windows libraries at build-time to provide this functionality.
+
+  4.10 My HTTP request using HEAD, PUT or DELETE does not work
+
+  Many web servers allow or demand that the administrator configures the
+  server properly for these requests to work on the web server.
+
+  Some servers seem to support HEAD only on certain kinds of URLs.
+
+  To fully grasp this, try the documentation for the particular server
+  software you are trying to interact with. This is not anything curl can do
+  anything about.
+
+  4.11 Why do my HTTP range requests return the full document?
+
+  Because the range may not be supported by the server, or the server may
+  choose to ignore it and return the full document anyway.
+
+  4.12 Why do I get "certificate verify failed" ?
+
+  When you invoke curl and get an error 60 error back it means that curl
+  could not verify that the server's certificate was good. curl verifies the
+  certificate using the CA cert bundle and verifying for which names the
+  certificate has been granted.
+
+  To completely disable the certificate verification, use -k. This does
+  however enable man-in-the-middle attacks and makes the transfer INSECURE.
+  We strongly advise against doing this for more than experiments.
+
+  If you get this failure with a CA cert bundle installed and used, the
+  server's certificate might not be signed by one of the CA's in your CA
+  store. It might for example be self-signed. You then correct this problem by
+  obtaining a valid CA cert for the server. Or again, decrease the security by
+  disabling this check.
+
+  At times, you find that the verification works in your favorite browser but
+  fails in curl. When this happens, the reason is usually that the server
+  sends an incomplete cert chain. The server is mandated to send all
+  "intermediate certificates" but does not. This typically works with browsers
+  anyway since they A) cache such certs and B) supports AIA which downloads
+  such missing certificates on demand. This is a server misconfiguration. A
+  good way to figure out if this is the case it to use the SSL Labs server
+  test and check the certificate chain: https://www.ssllabs.com/ssltest/
+
+  Details are also in the SSLCERTS.md document, found online here:
+  https://curl.se/docs/sslcerts.html
+
+  4.13 Why is curl -R on Windows one hour off?
+
+  Since curl 7.53.0 this issue should be fixed as long as curl was built with
+  any modern compiler that allows for a 64-bit curl_off_t type. For older
+  compilers or prior curl versions it may set a time that appears one hour off.
+  This happens due to a flaw in how Windows stores and uses file modification
+  times and it is not easily worked around. For more details read this:
+  https://www.codeproject.com/Articles/1144/Beating-the-Daylight-Savings-Time-bug-and-getting
+
+  4.14 Redirects work in browser but not with curl
+
+  curl supports HTTP redirects well (see item 3.8). Browsers generally support
+  at least two other ways to perform redirects that curl does not:
+
+  Meta tags. You can write an HTML tag that will cause the browser to redirect
+  to another given URL after a certain time.
+
+  JavaScript. You can write a JavaScript program embedded in an HTML page that
+  redirects the browser to another given URL.
+
+  There is no way to make curl follow these redirects. You must either
+  manually figure out what the page is set to do, or write a script that parses
+  the results and fetches the new URL.
+
+  4.15 FTPS does not work
+
+  curl supports FTPS (sometimes known as FTP-SSL) both implicit and explicit
+  mode.
+
+  When a URL is used that starts with FTPS://, curl assumes implicit SSL on
+  the control connection and will therefore immediately connect and try to
+  speak SSL. FTPS:// connections default to port 990.
+
+  To use explicit FTPS, you use an FTP:// URL and the --ftp-ssl option (or one
+  of its related flavors). This is the most common method, and the one
+  mandated by RFC4217. This kind of connection will then of course use the
+  standard FTP port 21 by default.
+
+  4.16 My HTTP POST or PUT requests are slow
+
+  libcurl makes all POST and PUT requests (except for POST requests with a
+  tiny request body) use the "Expect: 100-continue" header. This header
+  allows the server to deny the operation early so that libcurl can bail out
+  before having to send any data. This is useful in authentication
+  cases and others.
+
+  However, many servers do not implement the Expect: stuff properly and if the
+  server does not respond (positively) within 1 second libcurl will continue
+  and send off the data anyway.
+
+  You can disable libcurl's use of the Expect: header the same way you disable
+  any header, using -H / CURLOPT_HTTPHEADER, or by forcing it to use HTTP 1.0.
+
+  4.17 Non-functional connect timeouts
+
+  In most Windows setups having a timeout longer than 21 seconds make no
+  difference, as it will only send 3 TCP SYN packets and no more. The second
+  packet sent three seconds after the first and the third six seconds after
+  the second. No more than three packets are sent, no matter how long the
+  timeout is set.
+
+  See option TcpMaxConnectRetransmissions on this page:
+  https://support.microsoft.com/en-us/kb/175523/en-us
+
+  Also, even on non-Windows systems there may run a firewall or anti-virus
+  software or similar that accepts the connection but does not actually do
+  anything else. This will make (lib)curl to consider the connection connected
+  and thus the connect timeout will not trigger.
+
+  4.18 file:// URLs containing drive letters (Windows, NetWare)
+
+  When using curl to try to download a local file, one might use a URL
+  in this format:
+
+  file://D:/blah.txt
+
+  you will find that even if D:\blah.txt does exist, curl returns a 'file
+  not found' error.
+
+  According to RFC 1738 (https://www.ietf.org/rfc/rfc1738.txt),
+  file:// URLs must contain a host component, but it is ignored by
+  most implementations. In the above example, 'D:' is treated as the
+  host component, and is taken away. Thus, curl tries to open '/blah.txt'.
+  If your system is installed to drive C:, that will resolve to 'C:\blah.txt',
+  and if that does not exist you will get the not found error.
+
+  To fix this problem, use file:// URLs with *three* leading slashes:
+
+  file:///D:/blah.txt
+
+  Alternatively, if it makes more sense, specify 'localhost' as the host
+  component:
+
+  file://localhost/D:/blah.txt
+
+  In either case, curl should now be looking for the correct file.
+
+  4.19 Why does not curl return an error when the network cable is unplugged?
+
+  Unplugging a cable is not an error situation. The TCP/IP protocol stack
+  was designed to be fault tolerant, so even though there may be a physical
+  break somewhere the connection should not be affected, just possibly
+  delayed. Eventually, the physical break will be fixed or the data will be
+  re-routed around the physical problem through another path.
+
+  In such cases, the TCP/IP stack is responsible for detecting when the
+  network connection is irrevocably lost. Since with some protocols it is
+  perfectly legal for the client to wait indefinitely for data, the stack may
+  never report a problem, and even when it does, it can take up to 20 minutes
+  for it to detect an issue. The curl option --keepalive-time enables
+  keep-alive support in the TCP/IP stack which makes it periodically probe the
+  connection to make sure it is still available to send data. That should
+  reliably detect any TCP/IP network failure.
+
+  TCP keep alive will not detect the network going down before the TCP/IP
+  connection is established (e.g. during a DNS lookup) or using protocols that
+  do not use TCP. To handle those situations, curl offers a number of timeouts
+  on its own. --speed-limit/--speed-time will abort if the data transfer rate
+  falls too low, and --connect-timeout and --max-time can be used to put an
+  overall timeout on the connection phase or the entire transfer.
+
+  A libcurl-using application running in a known physical environment (e.g.
+  an embedded device with only a single network connection) may want to act
+  immediately if its lone network connection goes down. That can be achieved
+  by having the application monitor the network connection on its own using an
+  OS-specific mechanism, then signaling libcurl to abort (see also item 5.13).
+
+  4.20 curl does not return error for HTTP non-200 responses
+
+  Correct. Unless you use -f (--fail).
+
+  When doing HTTP transfers, curl will perform exactly what you are asking it
+  to do and if successful it will not return an error. You can use curl to
+  test your web server's "file not found" page (that gets 404 back), you can
+  use it to check your authentication protected web pages (that gets a 401
+  back) and so on.
+
+  The specific HTTP response code does not constitute a problem or error for
+  curl. It simply sends and delivers HTTP as you asked and if that worked,
+  everything is fine and dandy. The response code is generally providing more
+  higher level error information that curl does not care about. The error was
+  not in the HTTP transfer.
+
+  If you want your command line to treat error codes in the 400 and up range
+  as errors and thus return a non-zero value and possibly show an error
+  message, curl has a dedicated option for that: -f (CURLOPT_FAILONERROR in
+  libcurl speak).
+
+  You can also use the -w option and the variable %{response_code} to extract
+  the exact response code that was returned in the response.
+
+5. libcurl Issues
+
+  5.1 Is libcurl thread-safe?
+
+  Yes.
+
+  We have written the libcurl code specifically adjusted for multi-threaded
+  programs. libcurl will use thread-safe functions instead of non-safe ones if
+  your system has such. Note that you must never share the same handle in
+  multiple threads.
+
+  There may be some exceptions to thread safety depending on how libcurl was
+  built. Please review the guidelines for thread safety to learn more:
+  https://curl.se/libcurl/c/threadsafe.html
+
+  5.2 How can I receive all data into a large memory chunk?
+
+  [ See also the examples/getinmemory.c source ]
+
+  You are in full control of the callback function that gets called every time
+  there is data received from the remote server. You can make that callback do
+  whatever you want. You do not have to write the received data to a file.
+
+  One solution to this problem could be to have a pointer to a struct that you
+  pass to the callback function. You set the pointer using the
+  CURLOPT_WRITEDATA option. Then that pointer will be passed to the callback
+  instead of a FILE * to a file:
+
+        /* imaginary struct */
+        struct MemoryStruct {
+          char *memory;
+          size_t size;
+        };
+
+        /* imaginary callback function */
+        size_t
+        WriteMemoryCallback(void *ptr, size_t size, size_t nmemb, void *data)
+        {
+          size_t realsize = size * nmemb;
+          struct MemoryStruct *mem = (struct MemoryStruct *)data;
+
+          mem->memory = (char *)realloc(mem->memory, mem->size + realsize + 1);
+          if (mem->memory) {
+            memcpy(&(mem->memory[mem->size]), ptr, realsize);
+            mem->size += realsize;
+            mem->memory[mem->size] = 0;
+          }
+          return realsize;
+        }
+
+  5.3 How do I fetch multiple files with libcurl?
+
+  libcurl has excellent support for transferring multiple files. You should
+  just repeatedly set new URLs with curl_easy_setopt() and then transfer it
+  with curl_easy_perform(). The handle you get from curl_easy_init() is not
+  only reusable, but you are even encouraged to reuse it if you can, as that
+  will enable libcurl to use persistent connections.
+
+  5.4 Does libcurl do Winsock initialization on win32 systems?
+
+  Yes, if told to in the curl_global_init() call.
+
+  5.5 Does CURLOPT_WRITEDATA and CURLOPT_READDATA work on win32 ?
+
+  Yes, but you cannot open a FILE * and pass the pointer to a DLL and have
+  that DLL use the FILE * (as the DLL and the client application cannot access
+  each others' variable memory areas). If you set CURLOPT_WRITEDATA you must
+  also use CURLOPT_WRITEFUNCTION as well to set a function that writes the
+  file, even if that simply writes the data to the specified FILE *.
+  Similarly, if you use CURLOPT_READDATA you must also specify
+  CURLOPT_READFUNCTION.
+
+  5.6 What about Keep-Alive or persistent connections?
+
+  curl and libcurl have excellent support for persistent connections when
+  transferring several files from the same server.  curl will attempt to reuse
+  connections for all URLs specified on the same command line/config file, and
+  libcurl will reuse connections for all transfers that are made using the
+  same libcurl handle.
+
+  When you use the easy interface the connection cache is kept within the easy
+  handle. If you instead use the multi interface, the connection cache will be
+  kept within the multi handle and will be shared among all the easy handles
+  that are used within the same multi handle.
+
+  5.7 Link errors when building libcurl on Windows
+
+  You need to make sure that your project, and all the libraries (both static
+  and dynamic) that it links against, are compiled/linked against the same run
+  time library.
+
+  This is determined by the /MD, /ML, /MT (and their corresponding /M?d)
+  options to the command line compiler. /MD (linking against MSVCRT dll) seems
+  to be the most commonly used option.
+
+  When building an application that uses the static libcurl library, you must
+  add -DCURL_STATICLIB to your CFLAGS. Otherwise the linker will look for
+  dynamic import symbols. If you are using Visual Studio, you need to instead
+  add CURL_STATICLIB in the "Preprocessor Definitions" section.
+
+  If you get a linker error like "unknown symbol __imp__curl_easy_init ..." you
+  have linked against the wrong (static) library. If you want to use the
+  libcurl.dll and import lib, you do not need any extra CFLAGS, but use one of
+  the import libraries below. These are the libraries produced by the various
+  lib/Makefile.* files:
+
+       Target:          static lib.   import lib for libcurl*.dll.
+       -----------------------------------------------------------
+       MinGW:           libcurl.a     libcurldll.a
+       MSVC (release):  libcurl.lib   libcurl_imp.lib
+       MSVC (debug):    libcurld.lib  libcurld_imp.lib
+       Borland:         libcurl.lib   libcurl_imp.lib
+
+  5.8 libcurl.so.X: open failed: No such file or directory
+
+  This is an error message you might get when you try to run a program linked
+  with a shared version of libcurl and your runtime linker (ld.so) could not
+  find the shared library named libcurl.so.X. (Where X is the number of the
+  current libcurl ABI, typically 3 or 4).
+
+  You need to make sure that ld.so finds libcurl.so.X. You can do that
+  multiple ways, and it differs somewhat between different operating systems.
+  They are usually:
+
+  * Add an option to the linker command line that specify the hard-coded path
+    the runtime linker should check for the lib (usually -R)
+
+  * Set an environment variable (LD_LIBRARY_PATH for example) where ld.so
+    should check for libs
+
+  * Adjust the system's config to check for libs in the directory where you have
+    put the library (like Linux's /etc/ld.so.conf)
+
+  'man ld.so' and 'man ld' will tell you more details
+
+  5.9 How does libcurl resolve host names?
+
+  libcurl supports a large number of name resolve functions. One of them is
+  picked at build-time and will be used unconditionally. Thus, if you want to
+  change name resolver function you must rebuild libcurl and tell it to use a
+  different function.
+
+  - The non-IPv6 resolver that can use one of four different host name resolve
+  calls (depending on what your system supports):
+
+      A - gethostbyname()
+      B - gethostbyname_r() with 3 arguments
+      C - gethostbyname_r() with 5 arguments
+      D - gethostbyname_r() with 6 arguments
+
+  - The IPv6-resolver that uses getaddrinfo()
+
+  - The c-ares based name resolver that uses the c-ares library for resolves.
+    Using this offers asynchronous name resolves.
+
+  - The threaded resolver (default option on Windows). It uses:
+
+      A - gethostbyname() on plain IPv4 hosts
+      B - getaddrinfo() on IPv6 enabled hosts
+
+  Also note that libcurl never resolves or reverse-lookups addresses given as
+  pure numbers, such as 127.0.0.1 or ::1.
+
+  5.10 How do I prevent libcurl from writing the response to stdout?
+
+  libcurl provides a default built-in write function that writes received data
+  to stdout. Set the CURLOPT_WRITEFUNCTION to receive the data, or possibly
+  set CURLOPT_WRITEDATA to a different FILE * handle.
+
+  5.11 How do I make libcurl not receive the whole HTTP response?
+
+  You make the write callback (or progress callback) return an error and
+  libcurl will then abort the transfer.
+
+  5.12 Can I make libcurl fake or hide my real IP address?
+
+  No. libcurl operates on a higher level. Besides, faking IP address would
+  imply sending IP packets with a made-up source address, and then you normally
+  get a problem with receiving the packet sent back as they would then not be
+  routed to you.
+
+  If you use a proxy to access remote sites, the sites will not see your local
+  IP address but instead the address of the proxy.
+
+  Also note that on many networks NATs or other IP-munging techniques are used
+  that makes you see and use a different IP address locally than what the
+  remote server will see you coming from. You may also consider using
+  https://www.torproject.org/ .
+
+  5.13 How do I stop an ongoing transfer?
+
+  With the easy interface you make sure to return the correct error code from
+  one of the callbacks, but none of them are instant. There is no function you
+  can call from another thread or similar that will stop it immediately.
+  Instead, you need to make sure that one of the callbacks you use returns an
+  appropriate value that will stop the transfer. Suitable callbacks that you
+  can do this with include the progress callback, the read callback and the
+  write callback.
+
+  If you are using the multi interface, you can also stop a transfer by
+  removing the particular easy handle from the multi stack at any moment you
+  think the transfer is done or when you wish to abort the transfer.
+
+  5.14 Using C++ non-static functions for callbacks?
+
+  libcurl is a C library, it does not know anything about C++ member functions.
+
+  You can overcome this "limitation" with relative ease using a static
+  member function that is passed a pointer to the class:
+
+     // f is the pointer to your object.
+     static size_t YourClass::func(void *buffer, size_t sz, size_t n, void *f)
+     {
+       // Call non-static member function.
+       static_cast<YourClass*>(f)->nonStaticFunction();
+     }
+
+     // This is how you pass pointer to the static function:
+     curl_easy_setopt(hcurl, CURLOPT_WRITEFUNCTION, YourClass::func);
+     curl_easy_setopt(hcurl, CURLOPT_WRITEDATA, this);
+
+  5.15 How do I get an FTP directory listing?
+
+  If you end the FTP URL you request with a slash, libcurl will provide you
+  with a directory listing of that given directory. You can also set
+  CURLOPT_CUSTOMREQUEST to alter what exact listing command libcurl would use
+  to list the files.
+
+  The follow-up question tends to be how is a program supposed to parse the
+  directory listing. How does it know what's a file and what's a directory and
+  what's a symlink etc. If the FTP server supports the MLSD command then it
+  will return data in a machine-readable format that can be parsed for type.
+  The types are specified by RFC3659 section 7.5.1. If MLSD is not supported
+  then you have to work with what you are given. The LIST output format is
+  entirely at the server's own liking and the NLST output does not reveal any
+  types and in many cases does not even include all the directory entries.
+  Also, both LIST and NLST tend to hide unix-style hidden files (those that
+  start with a dot) by default so you need to do "LIST -a" or similar to see
+  them.
+
+  Example - List only directories.
+  ftp.funet.fi supports MLSD and ftp.kernel.org does not:
+
+     curl -s ftp.funet.fi/pub/ -X MLSD | \
+       perl -lne 'print if s/(?:^|;)type=dir;[^ ]+ (.+)$/$1/'
+
+     curl -s ftp.kernel.org/pub/linux/kernel/ | \
+       perl -lne 'print if s/^d[-rwx]{9}(?: +[^ ]+){7} (.+)$/$1/'
+
+  If you need to parse LIST output in libcurl one such existing
+  list parser is available at https://cr.yp.to/ftpparse.html  Versions of
+  libcurl since 7.21.0 also provide the ability to specify a wildcard to
+  download multiple files from one FTP directory.
+
+  5.16 I want a different time-out
+
+  Sometimes users realize that CURLOPT_TIMEOUT and CURLOPT_CONNECTIMEOUT are
+  not sufficiently advanced or flexible to cover all the various use cases and
+  scenarios applications end up with.
+
+  libcurl offers many more ways to time-out operations. A common alternative
+  is to use the CURLOPT_LOW_SPEED_LIMIT and CURLOPT_LOW_SPEED_TIME options to
+  specify the lowest possible speed to accept before to consider the transfer
+  timed out.
+
+  The most flexible way is by writing your own time-out logic and using
+  CURLOPT_XFERINFOFUNCTION (perhaps in combination with other callbacks) and
+  use that to figure out exactly when the right condition is met when the
+  transfer should get stopped.
+
+  5.17 Can I write a server with libcurl?
+
+  No. libcurl offers no functions or building blocks to build any kind of
+  Internet protocol server. libcurl is only a client-side library. For server
+  libraries, you need to continue your search elsewhere but there exist many
+  good open source ones out there for most protocols you could want a server
+  for. There are also really good stand-alone servers that have been tested
+  and proven for many years. There is no need for you to reinvent them.
+
+  5.18 Does libcurl use threads?
+
+  Put simply: no, libcurl will execute in the same thread you call it in. All
+  callbacks will be called in the same thread as the one you call libcurl in.
+
+  If you want to avoid your thread to be blocked by the libcurl call, you make
+  sure you use the non-blocking multi API which will do transfers
+  asynchronously - still in the same single thread.
+
+  libcurl will potentially internally use threads for name resolving, if it
+  was built to work like that, but in those cases it will create the child
+  threads by itself and they will only be used and then killed internally by
+  libcurl and never exposed to the outside.
+
+6. License Issues
+
+  curl and libcurl are released under a MIT/X derivative license. The license
+  is liberal and should not impose a problem for your project. This section is
+  just a brief summary for the cases we get the most questions. (Parts of this
+  section was much enhanced by Bjorn Reese.)
+
+  We are not lawyers and this is not legal advice. You should probably consult
+  one if you want true and accurate legal insights without our prejudice. Note
+  especially that this section concerns the libcurl license only; compiling in
+  features of libcurl that depend on other libraries (e.g. OpenSSL) may affect
+  the licensing obligations of your application.
+
+  6.1 I have a GPL program, can I use the libcurl library?
+
+  Yes
+
+  Since libcurl may be distributed under the MIT/X derivative license, it can
+  be used together with GPL in any software.
+
+  6.2 I have a closed-source program, can I use the libcurl library?
+
+  Yes
+
+  libcurl does not put any restrictions on the program that uses the library.
+
+  6.3 I have a BSD licensed program, can I use the libcurl library?
+
+  Yes
+
+  libcurl does not put any restrictions on the program that uses the library.
+
+  6.4 I have a program that uses LGPL libraries, can I use libcurl?
+
+  Yes
+
+  The LGPL license does not clash with other licenses.
+
+  6.5 Can I modify curl/libcurl for my program and keep the changes secret?
+
+  Yes
+
+  The MIT/X derivative license practically allows you to do almost anything
+  with the sources, on the condition that the copyright texts in the sources
+  are left intact.
+
+  6.6 Can you please change the curl/libcurl license to XXXX?
+
+  No.
+
+  We have carefully picked this license after years of development and
+  discussions and a large amount of people have contributed with source code
+  knowing that this is the license we use. This license puts the restrictions
+  we want on curl/libcurl and it does not spread to other programs or
+  libraries that use it. It should be possible for everyone to use libcurl or
+  curl in their projects, no matter what license they already have in use.
+
+  6.7 What are my obligations when using libcurl in my commercial apps?
+
+  Next to none. All you need to adhere to is the MIT-style license (stated in
+  the COPYING file) which basically says you have to include the copyright
+  notice in "all copies" and that you may not use the copyright holder's name
+  when promoting your software.
+
+  You do not have to release any of your source code.
+
+  You do not have to reveal or make public any changes to the libcurl source
+  code.
+
+  You do not have to broadcast to the world that you are using libcurl within
+  your app.
+
+  All we ask is that you disclose "the copyright notice and this permission
+  notice" somewhere. Most probably like in the documentation or in the section
+  where other third party dependencies already are mentioned and acknowledged.
+
+  As can be seen here: https://curl.se/docs/companies.html and elsewhere,
+  more and more companies are discovering the power of libcurl and take
+  advantage of it even in commercial environments.
+
+
+7. PHP/CURL Issues
+
+  7.1 What is PHP/CURL?
+
+  The module for PHP that makes it possible for PHP programs to access curl-
+  functions from within PHP.
+
+  In the cURL project we call this module PHP/CURL to differentiate it from
+  curl the command line tool and libcurl the library. The PHP team however
+  does not refer to it like this (for unknown reasons). They call it plain
+  CURL (often using all caps) or sometimes ext/curl, but both cause much
+  confusion to users which in turn gives us a higher question load.
+
+  7.2 Who wrote PHP/CURL?
+
+  PHP/CURL was initially written by Sterling Hughes.
+
+  7.3 Can I perform multiple requests using the same handle?
+
+  Yes - at least in PHP version 4.3.8 and later (this has been known to not
+  work in earlier versions, but the exact version when it started to work is
+  unknown to me).
+
+  After a transfer, you just set new options in the handle and make another
+  transfer. This will make libcurl re-use the same connection if it can.
+
+  7.4 Does PHP/CURL have dependencies?
+
+  PHP/CURL is a module that comes with the regular PHP package. It depends on
+  and uses libcurl, so you need to have libcurl installed properly before
+  PHP/CURL can be used.
+
+8. Development
+
+ 8.1 Why does curl use C89?
+
+ As with everything in curl, there is a history and we keep using what we have
+ used before until someone brings up the subject and argues for and works on
+ changing it.
+
+ We started out using C89 in the 1990s because that was the only way to write
+ a truly portable C program and have it run as widely as possible. C89 was for
+ a long time even necessary to make things work on otherwise considered modern
+ platforms such as Windows. Today, we do not really know how many users that
+ still require the use of a C89 compiler.
+
+ We will continue to use C89 for as long as nobody brings up a strong enough
+ reason for us to change our minds. The core developers of the project do not
+ feel restricted by this and we are not convinced that going C99 will offer us
+ enough of a benefit to warrant the risk of cutting off a share of users.
+
+ 8.2 Will curl be rewritten?
+
+ In one go: no. Little by little over time? Maybe.
+
+ Over the years, new languages and clever operating environments come and go.
+ Every now and then the urge apparently arises to request that we rewrite curl
+ in another language.
+
+ Some the most important properties in curl are maintaining the API and ABI
+ for libcurl and keeping the behavior for the command line tool. As long as we
+ can do that, everything else is up for discussion. To maintain the ABI, we
+ probably have to maintain a certain amount of code in C, and to remain rock
+ stable, we will never risk anything by rewriting a lot of things in one go.
+ That said, we can certainly offer more and more optional backends written in
+ other languages, as long as those backends can be plugged in at build-time.
+ Backends can be written in any language, but should probably provide APIs
+ usable from C to ease integration and transition.