faq

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    configure. Make sure that you remove the config.cache file before you
    rerun configure with the new flags.

  2.2. Does curl work/build with other SSL libraries?

  Curl has been written to use OpenSSL, although there should not be much
  problems using a different library. If anyone does "port" curl to use a
  different SSL library, we are of course very interested in getting the
  patch!

  2.3. Where can I find a copy of LIBEAY32.DLL?

  That is an OpenSSL binary built for Windows.

  Curl uses OpenSSL to do the SSL stuff. The LIBEAY32.DLL is what curl needs
  on a windows machine to do https://. Check out the curl web site to find
  accurate and up-to-date pointers to recent OpenSSL DLLs and other binary
  packages.

  2.4. Does cURL support Socks (RFC 1928) ?

  There is limited support for SOCKS5 for curl built with IPv6 support
  disabled.


3. Usage problems

  3.1. curl: (1) SSL is disabled, https: not supported

  If you get this output when trying to get anything from a https:// server,
  it means that the configure script couldn't find all libs and include files
  it 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 doesn't find the SSL libs
  and/or include files.

  Also, check out the other paragraph in this FAQ labeled "configure doesn't
  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 doesn't my posting using -F work?

  You can't simply use -F or -d at your choice. The web server that will
  receive your post assumes one of the formats. If the form you're trying to
  "fake" sets the type to '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 don't 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 don't use curl to just perform
  FTP commands without transferring anything. Therefore you must always specify
  a URL to transfer to/from even when doing custom FTP commands.

  3.5. How can I disable the Pragma: nocache 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 "Pragma:" to disable that specific header.

  3.6. Does curl support ASP, XML, XHTML or HTML version Y?

  To curl, all contents are alike. It doesn't matter how the page was
  generated. It may be ASP, PHP, Perl, shell-script, SSI or plain
  HTML-files. There's no difference to curl and it doesn't 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'

  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're using the
  -L/--location option. As in:

     curl -L http://redirector.com

  3.9 How do I use curl in my favorite programming language?

  There exist many language interfaces/bindings for curl that integrates it
  better with various languages. If you are fluid in a script language, you
  may very well opt to use such an interface instead of using the command line
  tool.

  Find out more about which languages that support curl directly, and how to
  install and use them, in the libcurl section of the curl web site:

        http://curl.haxx.se/libcurl/

  In February 2003, there are interfaces available for the following
  languages: Basic, C, C++, Cocoa, Dylan, Euphoria, Java, Lua, Object-Pascal,
  Pascal, Perl, PHP, PostgreSQL, Python, Rexx, Ruby, Scheme and Tcl. 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 fine and you'd 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 a HTTP proxy, the protocol spoken on the network will
  be HTTP, even if you specify a FTP URL. This effectively means that you
  normally can't 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
  other ports than 443 (which is used for HTTPS access through proxies).

  3.13 Why does 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 prompts I believe you're forced to use double (") quotes.

  Please study the documentation for your particular environment. Examples in
  the curl docs will use a mix of both these ones 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 doesn't support javascript,
  it can't support .pac proxy configuration either.

  Some work-arounds 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 interpreted, people have successfully used the
      Mozilla javascript engine in the past.

    - Ask your admins to stop this, for a static proxy setup or similar.


4. Running Problems

  4.1. Problems connecting to SSL servers.

  It took a very long time before we could sort out why curl had problems to
  connect to certain SSL servers when using SSLeay or OpenSSL v0.9+.  The
  error sometimes showed up similar to:

  16570:error:1407D071:SSL routines:SSL2_READ:bad mac decode:s2_pkt.c:233:

  It turned out to be because many older SSL servers don't deal with SSLv3
  requests properly. To correct this problem, tell curl to select SSLv2 from
  the command line (-2/--sslv2).

  There has also been examples where the remote server didn't like the SSLv2
  request and instead you had to force curl to use SSLv3 with -3/--sslv3.

  4.2. Why do I get problems when I use & or % in the URL?

  In general unix shells, the & letter is treated special 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.

  An example that would invoke a remote CGI that uses &-letters could be:

     curl 'http://www.altavista.com/cgi-bin/query?text=yes&q=curl'

  In Windows, the standard DOS shell treats the %-letter specially and you
  need to use TWO %-letters for each single one you want to use in the URL.

  Also note that if you want the literal %-letter 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 %-letter 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, and to be used in
  a URL specified to curl you must quote them.

  An example that downloads two URLs (sequentially) would do:

    curl '{curl,www}.haxx.se'

  To be able to use those letters 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 doesn't exist?

  Curl asks remote servers for the page you specify. If the page doesn't 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's simply how
  HTTP works.

  By using the --fail option you can tell curl explicitly to not get any data
  if the HTTP return code doesn't say success.

  4.5 Why do I get return code XXX from a 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"