---
name: "IO::Async::PID"
section: "3pm"
platform: "linux"
package: "libio-async-perl"
version: "0.804-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/IO::Async::PID"
---

# IO::Async::PID(3pm)

event callback on exit of a child process

## NAME

"IO::Async::PID" - event callback on exit of a child process

## SYNOPSIS

```
   use IO::Async::PID;
   use POSIX qw( WEXITSTATUS );
   use IO::Async::Loop;
   my $loop = IO::Async::Loop->new;
   my $kid = $loop->fork(
      code => sub {
         print "Child sleeping..\n";
         sleep 10;
         print "Child exiting\n";
         return 20;
      },
   );
   print "Child process $kid started\n";
   my $pid = IO::Async::PID->new(
      pid => $kid,
      on_exit => sub {
         my ( $self, $exitcode ) = @_;
         printf "Child process %d exited with status %d\n",
            $self->pid, WEXITSTATUS($exitcode);
      },
   );
   $loop->add( $pid );
   $loop->run;
```

## DESCRIPTION

This subclass of IO::Async::Notifier invokes its callback when a process exits.

For most use cases, a IO::Async::Process object provides more control of setting up the process, connecting filehandles to it, sending data to and receiving data from it.

## EVENTS

The following events are invoked, either using subclass methods or CODE references in parameters:

### on\_exit $exitcode

Invoked when the watched process exits.

## PARAMETERS

The following named parameters may be passed to `"new"` or `"configure"`:

### pid =\> INT

The process ID to watch. Must be given before the object has been added to the containing IO::Async::Loop object.

### on\_exit =\> CODE

CODE reference for the `"on_exit"` event.

Once the `"on_exit"` continuation has been invoked, the `"IO::Async::PID"` object is removed from the containing IO::Async::Loop object.

## METHODS

### pid

```
   $process_id = $pid->pid;
```

Returns the underlying process ID

### kill

```
   $pid->kill( $signal );
```

Sends a signal to the process

## AUTHOR

Paul Evans \<leonerd@leonerd.org.uk\>