glib-spawning-processes.html

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<a class="link" href="glib-Spawning-Processes.html#G-SPAWN-STDERR-TO-DEV-NULL:CAPS"><code class="literal">G_SPAWN_STDERR_TO_DEV_NULL</code></a> means that the child's standard error
will be discarded, instead of going to the same location as the parent's
standard error. If you use this flag, <em class="parameter"><code>standard_error</code></em> must be <a class="link" href="glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a>.
<a class="link" href="glib-Spawning-Processes.html#G-SPAWN-CHILD-INHERITS-STDIN:CAPS"><code class="literal">G_SPAWN_CHILD_INHERITS_STDIN</code></a> means that the child will inherit the parent's
standard input (by default, the child's standard input is attached to
/dev/null). If you use this flag, <em class="parameter"><code>standard_input</code></em> must be <a class="link" href="glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a>.
<a class="link" href="glib-Spawning-Processes.html#G-SPAWN-FILE-AND-ARGV-ZERO:CAPS"><code class="literal">G_SPAWN_FILE_AND_ARGV_ZERO</code></a> means that the first element of <em class="parameter"><code>argv</code></em> is
the file to execute, while the remaining elements are the
actual argument vector to pass to the file. Normally
<a class="link" href="glib-Spawning-Processes.html#g-spawn-async-with-pipes"><code class="function">g_spawn_async_with_pipes()</code></a> uses <em class="parameter"><code>argv</code></em>[0] as the file to execute, and
passes all of <em class="parameter"><code>argv</code></em> to the child.
</p>
<p>
<em class="parameter"><code>child_setup</code></em> and <em class="parameter"><code>user_data</code></em> are a function and user data. On POSIX
platforms, the function is called in the child after GLib has
performed all the setup it plans to perform (including creating
pipes, closing file descriptors, etc.) but before calling
<code class="function">exec()</code>. That is, <em class="parameter"><code>child_setup</code></em> is called just
before calling <code class="function">exec()</code> in the child. Obviously
actions taken in this function will only affect the child, not the
parent. On Windows, there is no separate <code class="function">fork()</code> and <code class="function">exec()</code>
functionality. Child processes are created and run with
a single API call, <code class="function">CreateProcess()</code>. <em class="parameter"><code>child_setup</code></em> is
called in the parent process just before creating the child
process. You should carefully consider what you do in <em class="parameter"><code>child_setup</code></em>
if you intend your software to be portable to Windows.
</p>
<p>
If non-<a class="link" href="glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a>, <em class="parameter"><code>child_pid</code></em> will on Unix be filled with the child's
process ID. You can use the process ID to send signals to the
child, or to use <a class="link" href="glib-The-Main-Event-Loop.html#g-child-watch-add"><code class="function">g_child_watch_add()</code></a> (or <code class="function">waitpid()</code>) if you specified the
<a class="link" href="glib-Spawning-Processes.html#G-SPAWN-DO-NOT-REAP-CHILD:CAPS"><code class="literal">G_SPAWN_DO_NOT_REAP_CHILD</code></a> flag. On Windows, <em class="parameter"><code>child_pid</code></em> will be
filled with a handle to the child process only if you specified the
<a class="link" href="glib-Spawning-Processes.html#G-SPAWN-DO-NOT-REAP-CHILD:CAPS"><code class="literal">G_SPAWN_DO_NOT_REAP_CHILD</code></a> flag. You can then access the child
process using the Win32 API, for example wait for its termination
with the <code class="function">WaitFor*()</code> functions, or examine its
exit code with <code class="function">GetExitCodeProcess()</code>. You should close the handle 
with <code class="function">CloseHandle()</code> or <a class="link" href="glib-Spawning-Processes.html#g-spawn-close-pid"><code class="function">g_spawn_close_pid()</code></a> when you no longer need it.
</p>
<p>
If non-<a class="link" href="glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a>, the <em class="parameter"><code>standard_input</code></em>, <em class="parameter"><code>standard_output</code></em>, <em class="parameter"><code>standard_error</code></em>
locations will be filled with file descriptors for writing to the child's
standard input or reading from its standard output or standard error.
The caller of <a class="link" href="glib-Spawning-Processes.html#g-spawn-async-with-pipes"><code class="function">g_spawn_async_with_pipes()</code></a> must close these file descriptors
when they are no longer in use. If these parameters are <a class="link" href="glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a>, the corresponding
pipe won't be created.
</p>
<p>
If <em class="parameter"><code>standard_input</code></em> is NULL, the child's standard input is attached to 
/dev/null unless <a class="link" href="glib-Spawning-Processes.html#G-SPAWN-CHILD-INHERITS-STDIN:CAPS"><code class="literal">G_SPAWN_CHILD_INHERITS_STDIN</code></a> is set.
</p>
<p>
If <em class="parameter"><code>standard_error</code></em> is NULL, the child's standard error goes to the same 
location as the parent's standard error unless <a class="link" href="glib-Spawning-Processes.html#G-SPAWN-STDERR-TO-DEV-NULL:CAPS"><code class="literal">G_SPAWN_STDERR_TO_DEV_NULL</code></a> 
is set.
</p>
<p>
If <em class="parameter"><code>standard_output</code></em> is NULL, the child's standard output goes to the same 
location as the parent's standard output unless <a class="link" href="glib-Spawning-Processes.html#G-SPAWN-STDOUT-TO-DEV-NULL:CAPS"><code class="literal">G_SPAWN_STDOUT_TO_DEV_NULL</code></a> 
is set.
</p>
<p>
<em class="parameter"><code>error</code></em> can be <a class="link" href="glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a> to ignore errors, or non-<a class="link" href="glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a> to report errors.
If an error is set, the function returns <a class="link" href="glib-Standard-Macros.html#FALSE:CAPS"><code class="literal">FALSE</code></a>. Errors
are reported even if they occur in the child (for example if the
executable in <code class="literal">argv[0]</code> is not found). Typically
the <code class="literal">message</code> field of returned errors should be displayed
to users. Possible errors are those from the <a class="link" href="glib-Spawning-Processes.html#G-SPAWN-ERROR:CAPS"><span class="type">G_SPAWN_ERROR</span></a> domain.
</p>
<p>
If an error occurs, <em class="parameter"><code>child_pid</code></em>, <em class="parameter"><code>standard_input</code></em>, <em class="parameter"><code>standard_output</code></em>,
and <em class="parameter"><code>standard_error</code></em> will not be filled with valid values.
</p>
<p>
If <em class="parameter"><code>child_pid</code></em> is not <a class="link" href="glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a> and an error does not occur then the returned
pid must be closed using <a class="link" href="glib-Spawning-Processes.html#g-spawn-close-pid"><code class="function">g_spawn_close_pid()</code></a>.
</p>
<p>
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<h3 class="title">Note</h3>
<p>
If you are writing a GTK+ application, and the program you 
are spawning is a graphical application, too, then you may
want to use <a
href="/usr/share/gtk-doc/html/gdk/GdkScreen.html#gdk-spawn-on-screen-with-pipes"
><code class="function">gdk_spawn_on_screen_with_pipes()</code></a> instead to ensure that 
the spawned program opens its windows no the right screen.
</p>
</div>
<p>

</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>working_directory</code></em>&#160;:</span></p></td>
<td> child's current working directory, or <a class="link" href="glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a> to inherit parent's, in the GLib file name encoding
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>argv</code></em>&#160;:</span></p></td>
<td> child's argument vector, in the GLib file name encoding
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>envp</code></em>&#160;:</span></p></td>
<td> child's environment, or <a class="link" href="glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a> to inherit parent's, in the GLib file name encoding
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>flags</code></em>&#160;:</span></p></td>
<td> flags from <a class="link" href="glib-Spawning-Processes.html#GSpawnFlags"><span class="type">GSpawnFlags</span></a>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>child_setup</code></em>&#160;:</span></p></td>
<td> function to run in the child just before <code class="function">exec()</code>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>user_data</code></em>&#160;:</span></p></td>
<td> user data for <em class="parameter"><code>child_setup</code></em>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>child_pid</code></em>&#160;:</span></p></td>
<td> return location for child process ID, or <a class="link" href="glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>standard_input</code></em>&#160;:</span></p></td>
<td> return location for file descriptor to write to child's stdin, or <a class="link" href="glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>standard_output</code></em>&#160;:</span></p></td>
<td> return location for file descriptor to read child's stdout, or <a class="link" href="glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>standard_error</code></em>&#160;:</span></p></td>
<td> return location for file descriptor to read child's stderr, or <a class="link" href="glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>error</code></em>&#160;:</span></p></td>
<td> return location for error
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span>&#160;:</span></p></td>
<td> <a class="link" href="glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> on success, <a class="link" href="glib-Standard-Macros.html#FALSE:CAPS"><code class="literal">FALSE</code></a> if an error was set
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id3100648"></a><h3>
<a name="g-spawn-async"></a>g_spawn_async ()</h3>
<a class="indexterm" name="id3100661"></a><pre class="programlisting"><a class="link" href="glib-Basic-Types.html#gboolean">gboolean</a>            g_spawn_async                       (const <a class="link" href="glib-Basic-Types.html#gchar">gchar</a> *working_directory,
                                                         <a class="link" href="glib-Basic-Types.html#gchar">gchar</a> **argv,
                                                         <a class="link" href="glib-Basic-Types.html#gchar">gchar</a> **envp,
                                                         <a class="link" href="glib-Spawning-Processes.html#GSpawnFlags">GSpawnFlags</a> flags,
                                                         <a class="link" href="glib-Spawning-Processes.html#GSpawnChildSetupFunc">GSpawnChildSetupFunc</a> child_setup,
                                                         <a class="link" href="glib-Basic-Types.html#gpointer">gpointer</a> user_data,
                                                         <a class="link" href="glib-The-Main-Event-Loop.html#GPid">GPid</a> *child_pid,
                                                         <a class="link" href="glib-Error-Reporting.html#GError">GError</a> **error);</pre>
<p>
See <a class="link" href="glib-Spawning-Processes.html#g-spawn-async-with-pipes"><code class="function">g_spawn_async_with_pipes()</code></a> for a full description; this function
simply calls the <a class="link" href="glib-Spawning-Processes.html#g-spawn-async-with-pipes"><code class="function">g_spawn_async_with_pipes()</code></a> without any pipes.
</p>
<p>
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<h3 class="title">Note</h3>
<p>
If you are writing a GTK+ application, and the program you 
are spawning is a graphical application, too, then you may
want to use <a
href="/usr/share/gtk-doc/html/gdk/GdkScreen.html#gdk-spawn-on-screen"
><code class="function">gdk_spawn_on_screen()</code></a> instead to ensure that 
the spawned program opens its windows on the right screen.
</p>
</div>
<p>

</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td><p><span class="term"><em class="parameter"><code>working_directory</code></em>&#160;:</span></p></td>
<td> child's current working directory, or <a class="link" href="glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a> to inherit parent's
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>argv</code></em>&#160;:</span></p></td>
<td> child's argument vector
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>envp</code></em>&#160;:</span></p></td>
<td> child's environment, or <a class="link" href="glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a> to inherit parent's
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>flags</code></em>&#160;:</span></p></td>
<td> flags from <a class="link" href="glib-Spawning-Processes.html#GSpawnFlags"><span class="type">GSpawnFlags</span></a>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>child_setup</code></em>&#160;:</span></p></td>
<td> function to run in the child just before <code class="function">exec()</code>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>user_data</code></em>&#160;:</span></p></td>
<td> user data for <em class="parameter"><code>child_setup</code></em>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>child_pid</code></em>&#160;:</span></p></td>
<td> return location for child process ID, or <a class="link" href="glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a>
</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>error</code></em>&#160;:</span></p></td>
<td> return location for error
</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span>&#160;:</span></p></td>
<td> <a class="link" href="glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> on success, <a class="link" href="glib-Standard-Macros.html#FALSE:CAPS"><code class="literal">FALSE</code></a> if error is set
</td>
</tr>
</tbody>
</table></div>
</div>