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kill(2) [bsd man page]

KILL(2) 							System Calls Manual							   KILL(2)

NAME
kill - send signal to a process SYNOPSIS
kill(pid, sig) int pid, sig; DESCRIPTION
Kill sends the signal sig to a process, specified by the process number pid. Sig may be one of the signals specified in sigvec(2), or it may be 0, in which case error checking is performed but no signal is actually sent. This can be used to check the validity of pid. The sending and receiving processes must have the same effective user ID, otherwise this call is restricted to the super-user. A single exception is the signal SIGCONT, which may always be sent to any descendant of the current process. If the process number is 0, the signal is sent to all processes in the sender's process group; this is a variant of killpg(2). If the process number is -1 and the user is the super-user, the signal is broadcast universally except to system processes and the process sending the signal. If the process number is -1 and the user is not the super-user, the signal is broadcast universally to all processes with the same uid as the user except the process sending the signal. No error is returned if any process could be signaled. For compatibility with System V, if the process number is negative but not -1, the signal is sent to all processes whose process group ID is equal to the absolute value of the process number. This is a variant of killpg(2). Processes may send signals to themselves. 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. ERRORS
Kill will fail and no signal will be sent if any of the following occur: [EINVAL] Sig is not a valid signal number. [ESRCH] No process can be found corresponding to that specified by pid. [ESRCH] The process id was given as 0 but the sending process does not have a process group. [EPERM] The sending process is not the super-user and its effective user id does not match the effective user-id of the receiving process. When signaling a process group, this error was returned if any members of the group could not be signaled. SEE ALSO
getpid(2), getpgrp(2), killpg(2), sigvec(2) 4th Berkeley Distribution May 14, 1986 KILL(2)

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KILL(2) 						      BSD System Calls Manual							   KILL(2)

NAME
kill -- send signal to a process SYNOPSIS
#include <signal.h> int kill(pid_t pid, int sig); DESCRIPTION
The kill() function sends the signal specified by sig to pid, a process or a group of processes. Typically, Sig will be one of the signals specified in sigaction(2). A value of 0, however, will cause error checking to be performed (with no signal being sent). This can be used to check the validity of pid. For a process to have permission to send a signal to a process designated by pid, the real or effective user ID of the receiving process must match that of the sending process or the user must have appropriate privileges (such as given by a set-user-ID program or the user is the super-user). A single exception is the signal SIGCONT, which may always be sent to any descendant of the current process. If pid is greater than zero: Sig is sent to the process whose ID is equal to pid. If pid is zero: Sig is sent to all processes whose group ID is equal to the process group ID of the sender, and for which the process has permission; this is a variant of killpg(2). If pid is -1: If the user has super-user privileges, the signal is sent to all processes excluding system processes and the process sending the signal. If the user is not the super user, the signal is sent to all processes with the same uid as the user, excluding the process sending the signal. No error is returned if any process could be signaled. For compatibility with System V, if the process number is negative but not -1, the signal is sent to all processes whose process group ID is equal to the absolute value of the process number. This is a variant of killpg(2). RETURN VALUES
Upon successful completion, a value of 0 is returned. Otherwise, a value of -1 is returned and errno is set to indicate the error. ERRORS
kill() will fail and no signal will be sent if: [EINVAL] Sig is not a valid, supported signal number. [EPERM] The sending process is not the super-user and its effective user id does not match the effective user-id of the receiving process. When signaling a process group, this error is returned if any members of the group could not be signaled. [ESRCH] No process or process group can be found corresponding to that specified by pid. [ESRCH] The process id was given as 0, but the sending process does not have a process group. SEE ALSO
getpgrp(2), getpid(2), killpg(2), sigaction(2) STANDARDS
The kill() function is expected to conform to IEEE Std 1003.1-1988 (``POSIX.1''). 4th Berkeley Distribution April 19, 1994 4th Berkeley Distribution

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