NAME

killpg − send signal to a process or a process group

SYNOPSIS

killpg(pgrp, sig)

cc ... −ljobs

DESCRIPTION

Killpg sends the signal sig to the specified process group.  See sigsys(2) for a list of signals; see intro(3J) 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 superuser.  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. 

RETURN VALUE

Upon successful completion, a value of 0 is returned.  Otherwise, a value of −1 is returned and errno is set to indicate the error. 

DIAGNOSTICS

Killpg will fail and no signal will be sent if any of the following occur:

[EINVAL] Sig is not a valid signal number. 

[EINVAL] Attempt to send to an unassigned process group. 

[EPERM] The caller is not the superuser. 

[ESRCH] No process can be found corresponding to the process group specified by pgrp.

[ESRCH] No processes killed. 

RESTRICTIONS

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. 

SEE ALSO

csh(1), kill(1), kill(2), signal(2), sigsys(2J), intro(3J)

ASSEMBLER (PDP-11)

(kill =37.) 
(process number in r0)
sys kill; −sig(negative signal number means killpg)