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@(#)killpg.2 4.1 (Berkeley) 05/09/85

C 4 killpg - send signal to a process or a process group killpg(pgrp, sig)

cc ... -ljobs

Killpg sends the signal sig to the specified process group. See sigsys (2) for a list of signals; see jobs (3) for an explanation of process groups.

The sending process and members of the process group must have the same effective user ID, otherwise this call is restricted to the super-user. As a single special case the continue signal SIGCONT may be sent to any process which is a descendant of the current process. This allows a command interpreter such as csh (1) to restart set-user-id processes stopped from the keyboard with a stop signal.

The calls

"killpg(0, sig)"

and

"kill(0, sig)

have identical effects, sending the signal to all members of the invoker's process group (including the process itself). It is preferable to use the call involving kill in this case, as it is portable to other UNIX systems.

jobs(3), kill(2), sigsys(2), signal(2), csh(1), kill(1) Zero is returned if the processes are sent the signals; -1 is returned if any process in the process group cannot be sent the signal, or if there are no members in the process group. The job control facilities are not available in standard version 7 UNIX. These facilities are still under development and may change in future releases of the system as better inter-process communication facilities and support for virtual terminals become available. The options and specifications of this system call and even the call itself are thus subject to change.