KILL(2) UNIX Programmer's Manual KILL(2) NAME kill - send signal to a process SYNOPSIS kill(pid, sig) int pid, sig; DESCRIPTION _K_i_l_l sends the signal _s_i_g to a process, specified by the process number _p_i_d. _S_i_g may be one of the signals specified in _s_i_g_v_e_c(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 _p_i_d. 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 _k_i_l_l_p_g(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 pro- cess 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 _k_i_l_l_p_g(2). Processes may send signals to themselves. RETURN VALUE Upon successful completion, a value of 0 is returned. Oth- erwise, a value of -1 is returned and _e_r_r_n_o is set to indi- cate the error. ERRORS _K_i_l_l will fail and no signal will be sent if any of the fol- lowing occur: [EINVAL] _S_i_g is not a valid signal number. [ESRCH] No process can be found corresponding to that specified by _p_i_d. Printed 11/26/99 May 14, 1986 1 KILL(2) UNIX Programmer's Manual KILL(2) [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) Printed 11/26/99 May 14, 1986 2