=item getpgrp PID
-Returns the current process group for the specified PID, 0 for the
+Returns the current process group for the specified PID. Use
+a PID of 0 to get the current process group for the
current process. Will raise an exception if used on a machine that
doesn't implement getpgrp(2). If PID is omitted, returns process
-group of current process.
+group of current process. Note that the POSIX version of getpgrp()
+does not accept a PID argument, so only PID==0 is truly portable.
=item getppid
Sets the current process group for the specified PID, 0 for the current
process. Will produce a fatal error if used on a machine that doesn't
-implement setpgrp(2).
+implement setpgrp(2). If the arguments are ommitted, it defaults to
+0,0. Note that the POSIX version of setpgrp() does not accept any
+arguments, so only setpgrp 0,0 is portable.
=item setpriority WHICH,WHO,PRIORITY
of the deceased process, or -1 if there is no such child process. The
status is returned in $?. If you say
- use POSIX "wait_h";
+ use POSIX ":wait_h";
...
waitpid(-1,&WNOHANG);