听vala中的背景过程

Question

我有一个要在后台听的命令Process.spawn_command_line_async是我想要的，但我不知道如何听响应。当需要更新时，该命令将输出行，然后我需要解析该行并相应地运行一个函数。进程在停止之前不会结束，因此需要在运行过程中进行监听。

Answer 1

您想要的是Process.spawn_commandline_async_with_pipes ()。Valadoc有一个代码示例：

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: %sn", stream_name, e.message);
return false;
} catch (ConvertError e) {
print ("%s: ConvertError: %sn", 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 ("/",
spawn_args,
spawn_env,
SpawnFlags.SEARCH_PATH | SpawnFlags.DO_NOT_REAP_CHILD,
null,
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 ();
});
loop.run ();
} catch (SpawnError e) {
print ("Error: %sn", e.message);
}
return 0;
}
valac --pkg glib-2.0 GLib.Process.spawn_async_with_pipes.vala