NAME

killpg − send signal to a process or a process group

SYNTAX

int killpg(pgrp, sig)
int pgrp, sig;

cc ... −ljobs

DESCRIPTION

The killpg system call sends the signal sig to process group pgrp. For a list of signals, see sigsys(2j). 

The following calls have identical effects:

killpg(0, sig)
 kill(0, sig)

They both have identical effects: send the signal to all members of the invoker’s process group (including the process itself). It is preferable to use the kill call in this case, however, because it is portable to other UNIX systems.  For an explanation of process groups, see intro(3j). 

RESTRICTIONS

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 special case, however, 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 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. 

RETURN VALUE

If unsuccessful, returns a −1, and the global variable errno indicates the error code. 

DIAGNOSTICS

The killpg call will fail if:

[EINVAL] The sig argument is not a valid signal number. 

[EINVAL] An attempt was made 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. 

SEE ALSO

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

ASSEMBLER

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