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28 .\" @(#)kill.2 8.3 (Berkeley) 4/19/94
29 .\" $FreeBSD: src/lib/libc/sys/kill.2,v 1.10.2.7 2001/12/14 18:34:01 ru Exp $
36 .Nd send signal to a process
43 .Fn kill "pid_t pid" "int sig"
47 function sends the signal given by
52 process or a group of processes.
54 may be one of the signals specified in
56 or it may be 0, in which case
57 error checking is performed but no
58 signal is actually sent.
59 This can be used to check the validity of
62 For a process to have permission to send a signal to a process designated
65 the real or effective user ID of the receiving process must match
66 that of the sending process or the user must have appropriate privileges
67 (such as given by a set-user-ID program or the user is the super-user).
68 A single exception is the signal
70 which may always be sent to any descendant of the current process.
72 .It \&If Fa pid No \&is greater than zero :
74 is sent to the process whose ID is equal to
76 .It \&If Fa pid No \&is zero :
78 is sent to all processes whose group ID is equal
79 to the process group ID of the sender, and for which the
80 process has permission;
83 .It \&If Fa pid No \&is -1 :
84 If the user has super-user privileges,
85 the signal is sent to all processes excluding
93 and the process sending the signal.
94 If the user is not the super user, the signal is sent to all processes
95 with the same uid as the user excluding the process sending the signal.
96 No error is returned if any process could be signaled.
99 NOTE! If the sending process is restricted by a reaper, the signal is
100 further restricted to processes only within or under that reaper.
101 The reaper itself can only be signalled directly.
103 For compatibility with System V,
104 if the process number is negative but not -1,
105 the signal is sent to all processes whose process group ID
106 is equal to the absolute value of the process number.
113 will fail and no signal will be sent if:
117 is not a valid signal number.
119 No process can be found corresponding to that specified by
122 The process id was given as 0
123 but the sending process does not have a process group.
125 The sending process is not the super-user and its effective
126 user id does not match the effective user-id of the receiving process.
127 When signaling a process group, this error is returned if any members
128 of the group could not be signaled.
141 function call is expected to conform to
146 function call appeared in