Description:

If any child processes have exited, this call will "reap" the zombies
similar to the perl "wait" function.

By default, it will return immediately and if there are no dead
children, everything will be undefined. If you pass in a true
argument, it will block until a child exits (or it gets a signal).

$pid PID of exiting child

$status exit status of child, just like C<$?>

$utime floating point user cpu seconds

$stime floating point system cpu seconds

$maxrss the maximum resident set size utilized (in kilobytes).

$minflt the number of page faults serviced without any I/O
activity; here I/O activity is avoided by "reclaiming" a
page frame from the list of pages awaiting reallocation.

$majflt the number of page faults serviced that required I/O
activity.

$nswap the number of times a process was "swapped" out of main
memory.

$inblock the number of times the file system had to perform input.

$oublock the number of times the file system had to perform output.

$msgsnd the number of messages sent over sockets.

$msgrcv the number of messages received from sockets.

$nsignals the number of signals delivered.

$nvcsw the number of times a context switch resulted due to a
process voluntarily giving up the processor before its
time slice was completed (usually to await availability of
a resource).

$nivcsw the number of times a context switch resulted due to a
higher priority process becoming runnable or because the
current process exceeded its time slice.