Object Hierarchy:

Object hierarchy for Pid


public struct Pid : int

A type which is used to hold a process identification.

On UNIX, processes are identified by a process id (an integer), while Windows uses process handles (which are pointers).

GPid is used in GLib only for descendant processes spawned with the g_spawn functions.

Example: Spawn with pipes, async:

private static bool process_line (IOChannel channel, IOCondition condition, string stream_name) {
if (condition == IOCondition.HUP) {
print ("%s: The fd has been closed.\n", stream_name);
return false;

try {
string line;
channel.read_line (out line, null, null);
print ("%s: %s", stream_name, line);
} catch (IOChannelError e) {
print ("%s: IOChannelError: %s\n", stream_name, e.message);
return false;
} catch (ConvertError e) {
print ("%s: ConvertError: %s\n", stream_name, e.message);
return false;

return true;

public static int main (string[] args) {
MainLoop loop = new MainLoop ();
try {
string[] spawn_args = {"ls", "-l", "-h"};
string[] spawn_env = Environ.get ();
Pid child_pid;

int standard_input;
int standard_output;
int standard_error;

Process.spawn_async_with_pipes ("/",
out child_pid,
out standard_input,
out standard_output,
out standard_error);

// stdout:
IOChannel output = new IOChannel.unix_new (standard_output);
output.add_watch (IOCondition.IN | IOCondition.HUP, (channel, condition) => {
return process_line (channel, condition, "stdout");

// stderr:
IOChannel error = new IOChannel.unix_new (standard_error);
error.add_watch (IOCondition.IN | IOCondition.HUP, (channel, condition) => {
return process_line (channel, condition, "stderr");

ChildWatch.add (child_pid, (pid, status) => {
// Triggered when the child indicated by child_pid exits
Process.close_pid (pid);
loop.quit ();
}); ();
} catch (SpawnError e) {
print ("Error: %s\n", e.message);
return 0;

valac --pkg glib-2.0 GLib.Process.spawn_async_with_pipes.vala

Namespace: GLib
Package: glib-2.0



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