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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 $
30 .\" $DragonFly: src/lib/libc/sys/kill.2,v 1.4 2007/12/08 23:20:29 swildner Exp $
37 .Nd send signal to a process
44 .Fn kill "pid_t pid" "int sig"
48 function sends the signal given by
53 process or a group of processes.
55 may be one of the signals specified in
57 or it may be 0, in which case
58 error checking is performed but no
59 signal is actually sent.
60 This can be used to check the validity of
63 For a process to have permission to send a signal to a process designated
66 the real or effective user ID of the receiving process must match
67 that of the sending process or the user must have appropriate privileges
68 (such as given by a set-user-ID program or the user is the super-user).
69 A single exception is the signal
71 which may always be sent to any descendant of the current process.
73 .It \&If Fa pid No \&is greater than zero :
75 is sent to the process whose ID is equal to
77 .It \&If Fa pid No \&is zero :
79 is sent to all processes whose group ID is equal
80 to the process group ID of the sender, and for which the
81 process has permission;
84 .It \&If Fa pid No \&is -1 :
85 If the user has super-user privileges,
86 the signal is sent to all processes excluding
94 and the process sending the signal.
95 If the user is not the super user, the signal is sent to all processes
96 with the same uid as the user excluding the process sending the signal.
97 No error is returned if any process could be signaled.
100 For compatibility with System V,
101 if the process number is negative but not -1,
102 the signal is sent to all processes whose process group ID
103 is equal to the absolute value of the process number.
110 will fail and no signal will be sent if:
114 is not a valid signal number.
116 No process can be found corresponding to that specified by
119 The process id was given as 0
120 but the sending process does not have a process group.
122 The sending process is not the super-user and its effective
123 user id does not match the effective user-id of the receiving process.
124 When signaling a process group, this error is returned if any members
125 of the group could not be signaled.
138 function call is expected to conform to
143 function call appeared in