kill(2)kill(2)NAMEkill(), raise() - send a signal to a process or a group of processes
SYNOPSISDESCRIPTION
The system call sends a signal to a process or a group of processes, as
specified by pid. The signal to be sent is specified by sig and is
either one from the list given in or
The system call sends a signal to the executing process or thread. The
signal to be sent is specified by sig and is either one from the list
given in or In a single-threaded process the effect of the function is
equivalent to calling
When used in a multithreaded program, the function sends the signal
specified by sig to the executing thread. The effect of the function
is equivalent to calling
If sig is (the null signal), error checking is performed but no signal
is actually sent. This can be used to check the validity of pid.
The real or effective user ID of the sending process must match the
real or saved user ID of the receiving process unless the sending
process has appropriate privileges.
As a single special case, the continue signal can be sent to any
process that is a member of the same session as the sending process.
The value is defined in the file and is guaranteed not to be the ID of
any process in the system or the negation of the ID of any process in
the system.
If pid is greater than zero and not equal to sig is sent to the process
whose process ID is equal to pid. pid can equal unless sig is or
If pid is sig is sent to all processes excluding special system pro‐
cesses whose process group ID is equal to the process group ID of the
sender.
If pid is and the sending process does not have the appropriate privi‐
leges, sig is sent to all processes excluding special system processes
whose real or saved user ID is equal to the real or effective user ID
of the sender.
If pid is and the effective user ID of the sender is a user who has
appropriate privileges, sig is sent to all processes excluding special
system processes.
If pid is behaves much as when pid is equal to except that sig is not
sent to the calling process.
If pid is negative but not or sig is sent to all processes (excluding
special system processes) whose process group ID is equal to the abso‐
lute value of pid, and whose real and/or effective user ID meets the
constraints described above for matching user IDs.
Security Restrictions
Some or all of the actions associated with this system call are subject
to compartmental restrictions. See compartments(5) for more information
about compartmentalization on systems that support that feature. Com‐
partmental restrictions can be overridden if the process possesses the
privilege (COMMALLOWED). Processes owned by the superuser may not have
this privilege. Processes owned by any user may have this privilege,
depending on system configuration.
Some or all of the actions associated with this system call require the
(OWNER) and/or the (REBOOT) privileges. Processes owned by the supe‐
ruser will have these privileges. Processes owned by other users may
have privilege(s), depending on system configuration. See privi‐
leges(5) for more information about privileged access on systems that
support fine-grained privileges.
RETURN VALUE
Upon successful completion, a value of is returned. Otherwise, a value
of is returned and is set to indicate the error.
ERRORS
If fails, no signal is sent. is set to one of the following values.
sig is neither a valid signal number nor zero.
sig is or and pid is that of the initialization
process (also known as
The user ID of the sending process is not a user who has
appropriate privileges and its real or effective
user ID does not match the real or saved user ID
of the receiving process.
The sending and receiving processes are not in the same session
and
the real or effective user ID does not match the
real or saved user ID of the receiving process.
No process or process group can be found corresponding to that
specified by
pid.
If fails, no signal is sent. is set to the following value.
sig is neither a valid signal number nor zero.
APPLICATION USAGE
Threads Considerations
can be used to post signals to another process but cannot be used to
post signals to a specific thread in another process. For information
on posting signals to specific threads within the same process, see
pthread_kill(3T).
LWP (Lightweight Processes) Considerations
Signals cannot be posted to specific LWPs in another process.
AUTHOR
was developed by HP, AT&T, and the University of California, Berkeley.
SEE ALSOkill(1), getpid(2), setsid(2), signal(2), sigqueue(2),
pthread_kill(3T).
STANDARDS CONFORMANCEkill(2)
