---
name: fork
status: documented
runtime: pp
source: src/runtime/pp/process.rs
---
```{index} single: fork; Perl built-in (pp runtime)
```

# fork

## Synopsis

```perl
my $pid = fork();
die "fork failed: $!" unless defined $pid;
if ($pid == 0) {
    # child process
    exit(0);
} else {
    # parent process, $pid is child's PID
    waitpid($pid, 0);
}
```

## Description

Creates a child process by duplicating the current process.

Calls POSIX `fork(2)` to create a new child process.  Both parent
and child continue execution from the point of the fork call.

Returns:
- `undef` on failure (fork could not be performed)
- `0` in the child process
- The child's PID (positive integer) in the parent process

## See also

exec, wait, waitpid, exit