sigsend, sigsendset - send a signal to a process or a group
int sigsend(idtype_t idtype, id_t id, int sig);
int sigsendset(procset_t *psp, int sig);
The sigsend() function sends a signal to the process or
group of processes specified by id and idtype. The signal to
be sent is specified by sig and is either 0 or one of the
values listed in signal(3HEAD). If sig is 0 (the null sig-
nal), error checking is performed but no signal is actually
sent. This value can be used to check the validity of id
The real or effective user ID of the sending process must
match the real or saved user ID of the receiving process,
unless the effective user ID of the sending process is
super-user, or sig is SIGCONT and the sending process has
the same session ID as the receiving process.
If idtype is P_PID, sig is sent to the process with process
If idtype is P_PGID, sig is sent to all processes with pro-
cess group ID id.
If idtype is P_SID, sig is sent to all processes with ses-
sion ID id.
If idtype is P_TASKID, sig is sent to all processes with
task ID id.
If idtype is P_UID, sig is sent to any process with effec-
tive user ID id.
If idtype is P_GID, sig is sent to any process with effec-
tive group ID id.
If idtype is P_PROJID, sig is sent to any process with pro-
ject ID id.
If idtype is P_CID, sig is sent to any process with
scheduler class ID id (see priocntl(2)).
If idtype is P_ALL, sig is sent to all processes and id is
If id is P_MYID, the value of id is taken from the calling
The process with a process ID of 0 is always excluded.
The process with a process ID of 1 is excluded unless
idtype is equal to P_PID.
The sigsendset() function provides an alternate interface
for sending signals to sets of processes. This function
sends signals to the set of processes specified by psp. psp
is a pointer to a structure of type procset_t, defined in
<sys/procset.h>, which includes the following members:
The p_lidtype and p_lid members specify the ID type and ID
of one ("left") set of processes; the p_ridtype and p_rid
members specify the ID type and ID of a second ("right") set
of processes. ID types and IDs are specified just as for the
idtype and id arguments to sigsend(). The p_op member speci-
fies the operation to be performed on the two sets of
processes to get the set of processes the function is to
apply to. The valid values for p_op and the processes they
Set difference: processes in left set and not in
Set intersection: processes in both left and right
Set union: processes in either left or right set or
Set exclusive-or: processes in left or right set but
not in both.
Upon successful completion, 0 is return. Otherwise, -1 is
returned and errno is set to indicate the error.
The sigsend() and sigsendset() functions will fail if:
The sig argument is not a valid signal number, or the
idtype argument is not a valid idtype field.
The sig argument is SIGKILL, idtype is P_PID and id
is 1 (proc1).
EPERM The effective user of the calling process is not
superuser and its real or effective user ID does not
match the real or effective user ID of the receiving
process, and the calling process is not sending
SIGCONT to a process that shares the same session.
ESRCH No process can be found corresponding to that speci-
fied by id and idtype.
The sigsendset() function will fail if:
The psp argument points to an illegal address.
kill(1), getpid(2), kill(2), priocntl(2), signal(3C),
Man(1) output converted with