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Technical Reference: Base Operating System and Extensions, Volume 1
Sends a signal to a process or to
a group of processes.
Standard C Library
(libc.a)
#include <sys/types.h>
#include <signal.h>
int kill(
Process,
Signal)
pid_t Process;
int Signal;
killpg(
ProcessGroup, Signal)
int ProcessGroup, Signal;
The kill subroutine
sends the signal specified by the Signal parameter to the process
or group of processes specified by the Process parameter.
To send a signal to another
process, either the real or the effective user ID of the sending process must
match the real or effective user ID of the receiving process, and the calling
process must have root user authority.
The processes that have the
process IDs of 0 and 1 are special processes and are sometimes referred to
here as proc0 and proc1, respectively.
Processes can send signals to
themselves.
Note: Sending a
signal does not imply that the operation is successful. All signal
operations must pass the access checks prescribed by each enforced access
control policy on the system.
| Process
| Specifies the ID of a process or group of processes.
If the Process parameter is greater than 0, the signal specified
by the Signal parameter is sent to the process identified by the
Process parameter.
If the Process parameter is 0, the signal specified by the
Signal parameter is sent to all processes, excluding
proc0 and proc1, whose process group ID matches the
process group ID of the sender.
If the value of the Process parameter is a negative value other
than -1 and if the calling process passes the access checks for the process to
be signaled, the signal specified by the Signal parameter is sent
to all the processes, excluding proc0 and proc1.
If the user ID of the calling process has root user authority, all processes,
excluding proc0 and proc1, are signaled.
If the value of the Process parameter is a negative value other
than -1, the signal specified by the Signal parameter is sent to
all processes having a process group ID equal to the absolute value of the
Process parameter.
If the value of the Process parameter is -1, the signal
specified by the Signal parameter is sent to all processes which
the process has permission to send that signal.
If pid is -1, sig will be sent to all processes (excluding an unspecified
set of system processes) for which the process has permission to send that
signal.
|
| Signal
| Specifies the signal. If the Signal parameter is a null value,
error checking is performed but no signal is sent. This parameter is
used to check the validity of the Process parameter.
|
| ProcessGroup
| Specifies the process group.
|
Upon successful completion, the
kill subroutine returns a value of 0. Otherwise, a value of
-1 is returned and the errno global variable is set to indicate the
error.
The kill subroutine is
unsuccessful and no signal is sent if one or more of the following are
true:
| EINVAL
| The Signal parameter is not a valid signal number.
|
| EINVAL
| The Signal parameter specifies the SIGKILL,
SIGSTOP, SIGTSTP, or SIGCONT signal, and the
Process parameter is 1 (proc1).
|
| ESRCH
| No process can be found corresponding to that specified by the
Process parameter.
|
| EPERM
| The real or effective user ID does not match the real or effective user
ID of the receiving process, or else the calling process does not have root
user authority.
|
These subroutines are part of
Base Operating System (BOS) Runtime.
The following interface is
provided for BSD Compatibility:
killpg(ProcessGroup, Signal)
int ProcessGroup; Signal;
This interface is equivalent
to:
if (ProcessGroup < 0)
{
errno = ESRCH;
return (-1);
}
return (kill(-ProcessGroup, Signal));
The getpid,
getpgrp, or getppid (getpid, getpgrp, or getppid Subroutine) subroutine, setpgid or
setpgrp subroutine, sigaction,
sigvec, or signal subroutine.
The kill command.
Signal
Management in AIX 5L Version 5.1 General Programming
Concepts: Writing and Debugging Programs provides more information
about signal management in multi-threaded processes.
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