spawn.sgml

GLib是GTK+和GNOME工程的基础底层核心程序库

<refsect2>
<title><anchor id="G-SPAWN-ERROR-CAPS">G_SPAWN_ERROR</title>
<programlisting>#define G_SPAWN_ERROR g_spawn_error_quark ()
</programlisting>
<para>
Error domain for spawning processes. Errors in this domain will
be from the <link linkend="GSpawnError">GSpawnError</link> enumeration. See <link linkend="GError">GError</link> for information on
error domains.
</para></refsect2>
<refsect2>
<title><anchor id="GSpawnFlags">enum GSpawnFlags</title>
<programlisting>typedef enum
{
  G_SPAWN_LEAVE_DESCRIPTORS_OPEN = 1 &lt;&lt; 0,
  G_SPAWN_DO_NOT_REAP_CHILD      = 1 &lt;&lt; 1,
  /* look for argv[0] in the path i.e. use execvp() */
  G_SPAWN_SEARCH_PATH            = 1 &lt;&lt; 2,
  /* Dump output to /dev/null */
  G_SPAWN_STDOUT_TO_DEV_NULL     = 1 &lt;&lt; 3,
  G_SPAWN_STDERR_TO_DEV_NULL     = 1 &lt;&lt; 4,
  G_SPAWN_CHILD_INHERITS_STDIN   = 1 &lt;&lt; 5,
  G_SPAWN_FILE_AND_ARGV_ZERO     = 1 &lt;&lt; 6
} GSpawnFlags;
</programlisting>
<para>
Flags passed to <link linkend="g-spawn-sync">g_spawn_sync</link>(), <link linkend="g-spawn-async">g_spawn_async</link>() and <link linkend="g-spawn-async-with-pipes">g_spawn_async_with_pipes</link>().
</para><informaltable pgwide="1" frame="none" role="enum">
<tgroup cols="2">
<colspec colwidth="2*">
<colspec colwidth="8*">
<tbody>
<row>
<entry><literal>G_SPAWN_LEAVE_DESCRIPTORS_OPEN</literal></entry>
<entry>the parent's open file descriptors will be 
 inherited by the child; otherwise all descriptors except stdin/stdout/stderr 
 will be closed before calling <function><link linkend="exec">exec</link>()</function> in the child.
</entry>
</row>
<row>
<entry><literal>G_SPAWN_DO_NOT_REAP_CHILD</literal></entry>
<entry>the child will not be automatically reaped; you 
  must call <function><link linkend="waitpid">waitpid</link>()</function> or handle <literal>SIGCHLD</literal> 
  yourself, or the child will become a zombie.
</entry>
</row>
<row>
<entry><literal>G_SPAWN_SEARCH_PATH</literal></entry>
<entry><literal>argv[0]</literal> need not be an absolute path, 
  it will be looked for in the user's <envar>PATH</envar>.
</entry>
</row>
<row>
<entry><literal>G_SPAWN_STDOUT_TO_DEV_NULL</literal></entry>
<entry>the child's standad output will be discarded, 
  instead of going to the same location as the parent's standard output.
</entry>
</row>
<row>
<entry><literal>G_SPAWN_STDERR_TO_DEV_NULL</literal></entry>
<entry>the child's standard error will be discarded.
</entry>
</row>
<row>
<entry><literal>G_SPAWN_CHILD_INHERITS_STDIN</literal></entry>
<entry>the child will inherit the parent's standard 
  input (by default, the child's standard input is attached to 
  <filename>/dev/null</filename>).
</entry>
</row>
<row>
<entry><literal>G_SPAWN_FILE_AND_ARGV_ZERO</literal></entry>
<entry>the first element of <literal>argv</literal> is 
  the file to execute, while the remaining elements are the actual argument 
  vector to pass to the file. Normally <link linkend="g-spawn-async-with-pipes">g_spawn_async_with_pipes</link>() uses 
  <literal>argv[0]</literal> as the file to execute, and passes all of 
  <literal>argv</literal> to the child.

</entry>
</row>
</tbody></tgroup></informaltable></refsect2>
<refsect2>
<title><anchor id="GSpawnChildSetupFunc">GSpawnChildSetupFunc ()</title>
<programlisting>void        (*GSpawnChildSetupFunc)         (<link linkend="gpointer">gpointer</link> user_data);</programlisting>
<para>
Specifies the type of the setup function passed to <link linkend="g-spawn-async">g_spawn_async</link>(),
<link linkend="g-spawn-sync">g_spawn_sync</link>() and <link linkend="g-spawn-async-with-pipes">g_spawn_async_with_pipes</link>(). It is called in the 
child after GLib has performed all the setup it plans to perform 
but before calling <function><link linkend="exec">exec</link>()</function>. Obviously, actions 
taken in this function will only affect the child, not the parent.
</para><informaltable pgwide="1" frame="none" role="params">
<tgroup cols="2">
<colspec colwidth="2*">
<colspec colwidth="8*">
<tbody>
<row><entry align="right"><parameter>user_data</parameter>&nbsp;:</entry>
<entry>user data to pass to the function.


</entry></row>
</tbody></tgroup></informaltable></refsect2>
<refsect2>
<title><anchor id="g-spawn-async-with-pipes">g_spawn_async_with_pipes ()</title>
<programlisting><link linkend="gboolean">gboolean</link>    g_spawn_async_with_pipes        (const <link linkend="gchar">gchar</link> *working_directory,
                                             <link linkend="gchar">gchar</link> **argv,
                                             <link linkend="gchar">gchar</link> **envp,
                                             <link linkend="GSpawnFlags">GSpawnFlags</link> flags,
                                             <link linkend="GSpawnChildSetupFunc">GSpawnChildSetupFunc</link> child_setup,
                                             <link linkend="gpointer">gpointer</link> user_data,
                                             <link linkend="gint">gint</link> *child_pid,
                                             <link linkend="gint">gint</link> *standard_input,
                                             <link linkend="gint">gint</link> *standard_output,
                                             <link linkend="gint">gint</link> *standard_error,
                                             <link linkend="GError">GError</link> **error);</programlisting>
<para>
Executes a child program asynchronously (your program will not
block waiting for the child to exit). The child program is
specified by the only argument that must be provided, <parameter>argv</parameter>. <parameter>argv</parameter>
should be a <literal>NULL</literal>-terminated array of strings, to be passed as the
argument vector for the child. The first string in <parameter>argv</parameter> is of
course the name of the program to execute. By default, the name of
the program must be a full path; the <envar>PATH</envar> shell variable 
will only be searched if you pass the <literal>G_SPAWN_SEARCH_PATH</literal> flag.
</para>
<para>
<parameter>envp</parameter> is a <literal>NULL</literal>-terminated array of strings, where each string
has the form <literal>KEY=VALUE</literal>. This will become
the child's environment. If <parameter>envp</parameter> is <literal>NULL</literal>, the child inherits its
parent's environment.
</para>
<para>
<parameter>flags</parameter> should be the bitwise OR of any flags you want to affect the
function's behavior. The <literal>G_SPAWN_DO_NOT_REAP_CHILD</literal> means that the
child will not be automatically reaped; you must call 
<function><link linkend="waitpid">waitpid</link>()</function> or handle <literal>SIGCHLD</literal> yourself, or the 
child will become a zombie.
<literal>G_SPAWN_LEAVE_DESCRIPTORS_OPEN</literal> means that the parent's open file
descriptors will be inherited by the child; otherwise all
descriptors except stdin/stdout/stderr will be closed before
calling <function><link linkend="exec">exec</link>()</function> in the child. <literal>G_SPAWN_SEARCH_PATH</literal> 
means that <literal>argv[0]</literal> need not be an absolute path, it
will be looked for in the user's <envar>PATH</envar>. 
<literal>G_SPAWN_STDOUT_TO_DEV_NULL</literal> means that the child's standad output will 
be discarded, instead of going to the same location as the parent's 
standard output.
<literal>G_SPAWN_STDERR_TO_DEV_NULL</literal> means that the child's standard error
will be discarded. <literal>G_SPAWN_CHILD_INHERITS_STDIN</literal> means that
the child will inherit the parent's standard input (by default,
the child's standard input is attached to /dev/null).
<literal>G_SPAWN_FILE_AND_ARGV_ZERO</literal> means that the first element of <parameter>argv</parameter> is
the file to execute, while the remaining elements are the
actual argument vector to pass to the file. Normally
<link linkend="g-spawn-async-with-pipes">g_spawn_async_with_pipes</link>() uses <parameter>argv</parameter>[0] as the file to execute, and
passes all of <parameter>argv</parameter> to the child.
</para>
<para>
<parameter>child_setup</parameter> and <parameter>user_data</parameter> are a function and user data to be
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 <function><link linkend="exec">exec</link>()</function>. That is, 
<parameter>child_setup</parameter> is called just before calling <function><link linkend="exec">exec</link>()</function> 
in the child. Obviously actions taken in this function will only affect 
the child, not the parent. 
</para>
<para>
If non-<literal>NULL</literal>, <parameter>child_pid</parameter> will be filled with the child's process
ID. You can use the process ID to send signals to the child, or
to <function><link linkend="waitpid">waitpid</link>()</function> if you specified the 
<literal>G_SPAWN_DO_NOT_REAP_CHILD</literal> flag.
</para>
<para>
If non-<literal>NULL</literal>, the <parameter>standard_input</parameter>, <parameter>standard_output</parameter>, <parameter>standard_error</parameter>
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 <link linkend="g-spawn-async-with-pipes">g_spawn_async_with_pipes</link>() must close these file descriptors
when they are no longer in use. If these parameters are <literal>NULL</literal>, the
corresponding pipe won't be created.
</para>
<para>
<parameter>error</parameter> can be <literal>NULL</literal> to ignore errors, or non-<literal>NULL</literal> to report errors.
If an error is set, the function returns <literal>FALSE</literal>. Errors
are reported even if they occur in the child (for example if the
executable in <literal>argv[0]</literal> is not found). Typically
the <literal>message</literal> field of returned errors should be displayed
to users. Possible errors are those from the <link linkend="G-SPAWN-ERROR-CAPS">G_SPAWN_ERROR</link> domain.
</para>
<para>
If an error occurs, <parameter>child_pid</parameter>, <parameter>standard_input</parameter>, <parameter>standard_output</parameter>,
and <parameter>standard_error</parameter> will not be filled with valid values.</para>
<para>

</para><informaltable pgwide="1" frame="none" role="params">
<tgroup cols="2">
<colspec colwidth="2*">
<colspec colwidth="8*">
<tbody>
<row><entry align="right"><parameter>working_directory</parameter>&nbsp;:</entry>
<entry> child's current working directory, or <literal>NULL</literal> to inherit parent's
</entry></row>
<row><entry align="right"><parameter>argv</parameter>&nbsp;:</entry>
<entry> child's argument vector
</entry></row>
<row><entry align="right"><parameter>envp</parameter>&nbsp;:</entry>
<entry> child's environment, or <literal>NULL</literal> to inherit parent's
</entry></row>
<row><entry align="right"><parameter>flags</parameter>&nbsp;:</entry>
<entry> flags from <link linkend="GSpawnFlags">GSpawnFlags</link>
</entry></row>
<row><entry align="right"><parameter>child_setup</parameter>&nbsp;:</entry>
<entry> function to run in the child just before <function><link linkend="exec">exec</link>()</function>
</entry></row>
<row><entry align="right"><parameter>user_data</parameter>&nbsp;:</entry>