waitpid - wait for a particular child process to die
waitpid PID,FLAGS
Waits for a particular child process to terminate and returns the pid of
the deceased process, or -1
if there is no such child process. The status is returned in $?
. If you say
use POSIX ":sys_wait_h"; #... waitpid(-1,&WNOHANG);
then you can do a non-blocking wait for any process. Non-blocking wait is available on machines supporting either the
waitpid(2)
or
wait4(2)
system calls. However, waiting for a particular pid with
FLAGS of
0
is implemented everywhere. (Perl emulates the system call by remembering
the status values of processes that have exited but have not been harvested
by the Perl script yet.)
See the perlipc manpage for other examples.
If rather than formatting bugs, you encounter substantive content errors in these documents, such as mistakes in the explanations or code, please use the perlbug utility included with the Perl distribution.