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1.\" $OpenBSD: kill.1,v 1.43 2025/04/24 14:15:29 schwarze Exp $
2.\" $NetBSD: kill.1,v 1.8 1995/09/07 06:30:26 jtc Exp $
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33.\"
34.\" @(#)kill.1 8.2 (Berkeley) 4/28/95
35.\"
36.Dd $Mdocdate: April 24 2025 $
37.Dt KILL 1
38.Os
39.Sh NAME
40.Nm kill
41.Nd terminate or signal a process
42.Sh SYNOPSIS
43.Nm kill
44.Op Fl Ar signal_number | Fl Ar signal_name | Fl s Ar signal_name
45.Ar pid ...
46.Nm kill
47.Fl l
48.Op Ar exit_status
49.Sh DESCRIPTION
50The
51.Nm
52utility sends a signal to the process(es) specified
53by the
54.Ar pid
55operand(s).
56If no signal is specified, the
57.Cm TERM
58signal is used.
59.Pp
60Only the superuser may send signals to other users' processes.
61.Pp
62The options are as follows:
63.Bl -tag -width Ds
64.It Fl l Op Ar exit_status
65Display the name of the signal corresponding to
66.Ar exit_status .
67.Ar exit_status
68may be the exit status of a command killed by a signal
69(see the
70special
71.Xr sh 1
72parameter
73.Sq ?\& )
74or a signal number.
75.Pp
76If no operand is given, display the names of all the signals.
77.It Fl Ar signal_number | Fl Ar signal_name | Fl s Ar signal_name
78A non-negative decimal integer or a symbolic name
79specifying the signal to be sent instead of the default
80.Cm TERM .
81.El
82.Pp
83The following PIDs have special meanings:
84.Bl -tag -width Ds -offset indent
85.It \-1
86If superuser, broadcast the signal to all processes; otherwise, broadcast
87to all processes belonging to the user.
88.It 0
89Send the signal to all processes whose group ID is equal to the
90process group ID of the sender, and for which the process has permission.
91.It \- Ns Ar pgid
92Send the signal to all processes within the specified process group.
93.El
94.Pp
95Some of the more commonly used signals:
96.Pp
97.Bl -column MM MMMM -compact -offset indent
98.It 1 Ta Cm HUP Ta Pq hang up
99.It 2 Ta Cm INT Ta Pq interrupt
100.It 3 Ta Cm QUIT Ta Pq quit
101.It 6 Ta Cm ABRT Ta Pq abort
102.It 9 Ta Cm KILL Ta Pq non-catchable, non-ignorable kill
103.It 14 Ta Cm ALRM Ta Pq alarm clock
104.It 15 Ta Cm TERM Ta Pq software termination signal
105.El
106.Pp
107For a complete list, consult the
108.Xr signal 3
109manual page.
110.Pp
111A signal number of 0
112.Pq Nm kill Fl 0 Ar pid
113does not send a signal, but only checks the validity of a certain PID.
114It succeeds if
115.Ar pid
116exists or raises an error otherwise.
117.Sh EXIT STATUS
118.Ex -std kill
119.Sh EXAMPLES
120Forcibly terminate process ID 1234:
121.Pp
122.Dl $ kill -9 1234
123.Pp
124Send the
125.Xr init 8
126process the hangup signal, instructing it to re-read
127.Xr ttys 5 :
128.Pp
129.Dl # kill -HUP 1
130.Sh SEE ALSO
131.Xr csh 1 ,
132.Xr ksh 1 ,
133.Xr pkill 1 ,
134.Xr ps 1 ,
135.Xr kill 2 ,
136.Xr signal 3
137.Sh STANDARDS
138The
139.Nm
140utility is compliant with the
141.St -p1003.1-2008
142specification.
143.Pp
144The
145.Fl Ar signal_name
146and
147.Fl Ar signal_number
148syntax is marked by
149.St -p1003.1-2008
150as being an
151X/Open System Interfaces
152option.
153.Pp
154.Nm
155also exists as a built-in to
156.Xr csh 1
157and
158.Xr ksh 1 ,
159though with a different syntax.
160.Sh HISTORY
161A
162.Nm
163command appeared in
164.At v3 .