.\" * | (__| |_| | _ <| |___
.\" * \___|\___/|_| \_\_____|
.\" *
-.\" * Copyright (C) 1998 - 2011, Daniel Stenberg, <daniel@haxx.se>, et al.
+.\" * Copyright (C) 1998 - 2014, Daniel Stenberg, <daniel@haxx.se>, et al.
.\" *
.\" * This software is licensed as described in the file COPYING, which
.\" * you should have received as part of this distribution. The terms
\fIlibcurl-share(3)\fP man page and the \fIlibcurl-tutorial(3)\fP man page for
in-depth understanding on how to program with libcurl.
-There are more than thirty custom bindings available that bring libcurl access
-to your favourite language. Look elsewhere for documentation on those.
+There are many bindings available that bring libcurl access to your favourite
+language. Look elsewhere for documentation on those.
-libcurl has a global constant environment that you must set up and
-maintain while using libcurl. This essentially means you call
+libcurl has a global constant environment that you must set up and maintain
+while using libcurl. This essentially means you call
\fIcurl_global_init(3)\fP at the start of your program and
-\fIcurl_global_cleanup(3)\fP at the end. See GLOBAL CONSTANTS below
-for details.
+\fIcurl_global_cleanup(3)\fP at the end. See \fBGLOBAL CONSTANTS\fP below for
+details.
-To transfer files, you always set up an "easy handle" using
-\fIcurl_easy_init(3)\fP, but when you want the file(s) transferred you have
-the option of using the "easy" interface, or the "multi" interface.
+To transfer files, you create an "easy handle" using \fIcurl_easy_init(3)\fP
+for a single individual transfer (in either direction). You then set your
+desired set of options in that handle with \fIcurl_easy_setopt(3)\fP. Options
+you set with \fIcurl_easy_setopt(3)\fP stick. They will be used on every
+repeated use of this handle until you either change the option, or you reset
+them all with \fIcurl_easy_reset(3)\fP.
+
+To actually transfer data you have the option of using the "easy" interface,
+or the "multi" interface.
The easy interface is a synchronous interface with which you call
\fIcurl_easy_perform(3)\fP and let it perform the transfer. When it is
call and that performs only a little piece of the transfer on each invoke. It
is perfect if you want to do things while the transfer is in progress, or
similar. The multi interface allows you to select() on libcurl action, and
-even to easily download multiple files simultaneously using a single thread. See further details in the \fIlibcurl-multi(3)\fP man page.
+even to easily download multiple files simultaneously using a single
+thread. See further details in the \fIlibcurl-multi(3)\fP man page.
You can have multiple easy handles share certain data, even if they are used
in different threads. This magic is setup using the share interface, as
often don't provide the curl-config tool, but simply install the library and
headers in the common path for this purpose.
+Many Linux and similar sytems use pkg-config to provide build and link options
+about libraries and libcurl supports that as well.
.SH "LIBCURL SYMBOL NAMES"
All public functions in the libcurl interface are prefixed with 'curl_' (with
a lowercase c). You can find other functions in the library source code, but
threads, but you must use separate curl handles if you want to use libcurl in
more than one thread simultaneously.
-The global environment functions are not thread-safe. See GLOBAL CONSTANTS
-below for details.
+The global environment functions are not thread-safe. See \fBGLOBAL
+CONSTANTS\fP below for details.
.SH "PERSISTENT CONNECTIONS"
Persistent connections means that libcurl can re-use the same connection for
several transfers, if the conditions are right.
libcurl will \fBalways\fP attempt to use persistent connections. Whenever you
-use \fIcurl_easy_perform(3)\fP or \fIcurl_multi_perform(3)\fP, libcurl will
-attempt to use an existing connection to do the transfer, and if none exists
-it'll open a new one that will be subject for re-use on a possible following
-call to \fIcurl_easy_perform(3)\fP or \fIcurl_multi_perform(3)\fP.
+use \fIcurl_easy_perform(3)\fP or \fIcurl_multi_perform(3)\fP etc, libcurl
+will attempt to use an existing connection to do the transfer, and if none
+exists it'll open a new one that will be subject for re-use on a possible
+following call to \fIcurl_easy_perform(3)\fP or \fIcurl_multi_perform(3)\fP.
To allow libcurl to take full advantage of persistent connections, you should
-do as many of your file transfers as possible using the same curl handle. When
-you call \fIcurl_easy_cleanup(3)\fP, all the possibly open connections held by
-libcurl will be closed and forgotten.
+do as many of your file transfers as possible using the same handle.
-Note that the options set with \fIcurl_easy_setopt(3)\fP will be used on
-every repeated \fIcurl_easy_perform(3)\fP call.
+If you use the easy interface, and you call \fIcurl_easy_cleanup(3)\fP, all
+the possibly open connections held by libcurl will be closed and forgotten.
+When you've created a multi handle and are using the multi interface, the
+connection pool is instead kept in the multi handle so closing and creating
+new easy handles to do transfers will not affect them. Instead all added easy
+handles can take advantage of the single shared pool.
.SH "GLOBAL CONSTANTS"
There are a variety of constants that libcurl uses, mainly through its
internal use of other libraries, which are too complicated for the
capability via the GNU TLS library, there is an elaborate tree inside
that library that describes the SSL protocol.
-\fIcurl_global_init()\fP is the function that you must call. This may
-allocate resources (e.g. the memory for the GNU TLS tree mentioned
-above), so the companion function \fIcurl_global_cleanup()\fP releases
-them.
+\fIcurl_global_init(3)\fP is the function that you must call. This may
+allocate resources (e.g. the memory for the GNU TLS tree mentioned above), so
+the companion function \fIcurl_global_cleanup(3)\fP releases them.
-The basic rule for constructing a program that uses libcurl is this:
-Call \fIcurl_global_init()\fP, with a \fICURL_GLOBAL_ALL\fP argument,
-immediately after the program starts, while it is still only one
-thread and before it uses libcurl at all. Call
-\fIcurl_global_cleanup()\fP immediately before the program exits, when
-the program is again only one thread and after its last use of
-libcurl.
+The basic rule for constructing a program that uses libcurl is this: Call
+\fIcurl_global_init(3)\fP, with a \fICURL_GLOBAL_ALL\fP argument, immediately
+after the program starts, while it is still only one thread and before it uses
+libcurl at all. Call \fIcurl_global_cleanup(3)\fP immediately before the
+program exits, when the program is again only one thread and after its last
+use of libcurl.
You can call both of these multiple times, as long as all calls meet
these requirements and the number of calls to each is the same.
know whether they use libcurl or not. And its code doesn't necessarily
run at the start and end of the whole program.
-A module like this must have global constant functions of its own,
-just like \fIcurl_global_init()\fP and \fIcurl_global_cleanup()\fP.
-The module thus has control at the beginning and end of the program
-and has a place to call the libcurl functions. Note that if multiple
-modules in the program use libcurl, they all will separately call the
-libcurl functions, and that's OK because only the first
-\fIcurl_global_init()\fP and the last \fIcurl_global_cleanup()\fP in a
-program change anything. (libcurl uses a reference count in static
-memory).
-
-In a C++ module, it is common to deal with the global constant
-situation by defining a special class that represents the global
-constant environment of the module. A program always has exactly one
-object of the class, in static storage. That way, the program
-automatically calls the constructor of the object as the program
-starts up and the destructor as it terminates. As the author of this
-libcurl-using module, you can make the constructor call
-\fIcurl_global_init()\fP and the destructor call
-\fIcurl_global_cleanup()\fP and satisfy libcurl's requirements without
-your user having to think about it.
-
-\fIcurl_global_init()\fP has an argument that tells what particular
-parts of the global constant environment to set up. In order to
-successfully use any value except \fICURL_GLOBAL_ALL\fP (which says to
-set up the whole thing), you must have specific knowledge of internal
-workings of libcurl and all other parts of the program of which it is
-part.
-
-A special part of the global constant environment is the identity of
-the memory allocator. \fIcurl_global_init()\fP selects the system
-default memory allocator, but you can use \fIcurl_global_init_mem()\fP
-to supply one of your own. However, there is no way to use
-\fIcurl_global_init_mem()\fP in a modular program -- all modules in
-the program that might use libcurl would have to agree on one
-allocator.
-
-There is a failsafe in libcurl that makes it usable in simple
-situations without you having to worry about the global constant
-environment at all: \fIcurl_easy_init()\fP sets up the environment
-itself if it hasn't been done yet. The resources it acquires to do so
-get released by the operating system automatically when the program
-exits.
+A module like this must have global constant functions of its own, just like
+\fIcurl_global_init(3)\fP and \fIcurl_global_cleanup(3)\fP. The module thus
+has control at the beginning and end of the program and has a place to call
+the libcurl functions. Note that if multiple modules in the program use
+libcurl, they all will separately call the libcurl functions, and that's OK
+because only the first \fIcurl_global_init(3)\fP and the last
+\fIcurl_global_cleanup(3)\fP in a program change anything. (libcurl uses a
+reference count in static memory).
+
+In a C++ module, it is common to deal with the global constant situation by
+defining a special class that represents the global constant environment of
+the module. A program always has exactly one object of the class, in static
+storage. That way, the program automatically calls the constructor of the
+object as the program starts up and the destructor as it terminates. As the
+author of this libcurl-using module, you can make the constructor call
+\fIcurl_global_init(3)\fP and the destructor call \fIcurl_global_cleanup(3)\fP
+and satisfy libcurl's requirements without your user having to think about it.
+
+\fIcurl_global_init(3)\fP has an argument that tells what particular parts of
+the global constant environment to set up. In order to successfully use any
+value except \fICURL_GLOBAL_ALL\fP (which says to set up the whole thing), you
+must have specific knowledge of internal workings of libcurl and all other
+parts of the program of which it is part.
+
+A special part of the global constant environment is the identity of the
+memory allocator. \fIcurl_global_init(3)\fP selects the system default memory
+allocator, but you can use \fIcurl_global_init_mem(3)\fP to supply one of your
+own. However, there is no way to use \fIcurl_global_init_mem(3)\fP in a
+modular program -- all modules in the program that might use libcurl would
+have to agree on one allocator.
+
+There is a failsafe in libcurl that makes it usable in simple situations
+without you having to worry about the global constant environment at all:
+\fIcurl_easy_init(3)\fP sets up the environment itself if it hasn't been done
+yet. The resources it acquires to do so get released by the operating system
+automatically when the program exits.
This failsafe feature exists mainly for backward compatibility because
there was a time when the global functions didn't exist. Because it
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