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

# waitpid

## Synopsis

```perl
my $result = waitpid($pid, 0);        # blocking wait
my $result = waitpid($pid, WNOHANG);  # non-blocking
my $result = waitpid(-1, 0);           # any child (like wait)
```

## Description

Waits for a specific child process to change state.

Suspends the current process until the child identified by `$pid`
terminates (or changes state, depending on flags).  Sets `$?` to
the wait status.

Returns:
- The PID of the terminated child on success
- `0` if `WNOHANG` was specified and no child has exited yet
- `-1` on error (e.g. no such child)

When `$pid` is `-1`, waits for any child (equivalent to `wait()`).

## See also

wait, fork, POSIX