misc-utils/kill.1

   1 .\" Copyright 1994 Salvatore Valente (svalente@mit.edu)
   2 .\" Copyright 1992 Rickard E. Faith (faith@cs.unc.edu)
   3 .\" May be distributed under the GNU General Public License
   4 .TH KILL 1 "July 2014" "util-linux" "User Commands"
   5 .SH NAME
   6 kill \- terminate a process
   7 .SH SYNOPSIS
   8 .B kill
   9 .RB [ \- \fIsignal\fR| \-s
  10 .IR signal | \fB-p\fP ]
  11 .RB [ \-q
  12 .IR value ]
  13 .RB [ \-a ]
  14 .RB [ \-\- ]
  15 .IR pid | name ...
  16 .br
  17 .B kill \-l
  18 .RI [ number ]
  19 .RB "| " \-L
  20 .SH DESCRIPTION
  21 The command
  22 .B kill
  23 sends the specified \fIsignal\fR to the specified processes or process groups.
  24 .PP
  25 If no signal is specified, the TERM signal is sent.
  26 The default action for this signal is to terminate the process.
  27 This signal should be used in preference to the
  28 KILL signal (number 9), since a process may install a handler for the
  29 TERM signal in order to perform clean-up steps before terminating in
  30 an orderly fashion.
  31 If a process does not terminate after a TERM signal has been sent,
  32 then the KILL signal may be used; be aware that the latter signal
  33 cannot be caught, and so does not give the target process the opportunity
  34 to perform any clean-up before terminating.
  35 .PP
  36 Most modern shells have a builtin kill command, with a usage rather similar to
  37 that of the command described here.  The
  38 .BR \-\-all ,
  39 .BR \-\-pid ", and"
  40 .B \-\-queue
  41 options, and the possibility to specify processes by command name, are local extensions.
  42 .PP
  43 If \fIsignal\fR is 0, then no actual signal is sent, but error checking is still performed.
  44
  45 .SH ARGUMENTS
  46 The list of processes to be signaled can be a mixture of names and PIDs.
  47 .TP
  48 .I pid
  49 Each
  50 .I pid
  51 can be one of four things:
  52 .RS
  53 .TP
  54 .I n
  55 where
  56 .I n
  57 is larger than 0.  The process with PID
  58 .I n
  59 is signaled.
  60 .TP
  61 .B 0
  62 All processes in the current process group are signaled.
  63 .TP
  64 .B -1
  65 All processes with a PID larger than 1 are signaled.
  66 .TP
  67 .BI - n
  68 where
  69 .I n
  70 is larger than 1.  All processes in process group
  71 .I n
  72 are signaled.  When an argument of the form '-n' is given, and it is meant to
  73 denote a process group, either a signal must be specified first, or the
  74 argument must be preceded by a '--' option, otherwise it will be taken as the
  75 signal to send.
  76 .RE
  77 .TP
  78 .I name
  79 All processes invoked using this \fIname\fR will be signaled.
  80
  81 .SH OPTIONS
  82 .TP
  83 \fB\-s\fR, \fB\-\-signal\fR \fIsignal\fR
  84 The signal to send.  It may be given as a name or a number.
  85 .TP
  86 \fB\-l\fR, \fB\-\-list\fR [\fInumber\fR]
  87 Print a list of signal names, or convert the given signal number to a name.
  88 The signals can be found in
  89 .I /usr/\:include/\:linux/\:signal.h
  90 .TP
  91 \fB\-L\fR, \fB\-\-table\fR
  92 Similar to \fB\-l\fR, but it will print signal names and their corresponding
  93 numbers.
  94 .TP
  95 \fB\-a\fR, \fB\-\-all\fR
  96 Do not restrict the command-name-to-PID conversion to processes with the same
  97 UID as the present process.
  98 .TP
  99 \fB\-p\fR, \fB\-\-pid\fR
 100 Only print the process ID (PID) of the named processes, do not send any
 101 signals.
 102 .TP
 103 \fB\-\-verbose\fR
 104 Print PID(s) that will be signaled with kill along with the signal.
 105 .TP
 106 \fB\-q\fR, \fB\-\-queue\fR \fIvalue\fR
 107 Use
 108 .BR sigqueue (3)
 109 rather than
 110 .BR kill (2).
 111 The
 112 .I value
 113 argument is an integer that is sent along with the signal.  If the
 114 receiving process has installed a handler for this signal using the
 115 .B SA_SIGINFO
 116 flag to
 117 .BR sigaction (2),
 118 then it can obtain this data via the
 119 .I si_sigval
 120 field of the
 121 .I siginfo_t
 122 structure.
 123
 124 .SH NOTES
 125 Although it is possible to specify the TID (thread ID, see
 126 .BR gettid (2))
 127 of one of the threads in a multithreaded process as the argument of
 128 .BR kill ,
 129 the signal is nevertheless directed to the process
 130 (i.e., the entire thread group).
 131 In other words, it is not possible to send a signal to an
 132 explicitly selected thread in a multithreaded process.
 133 The signal will be delivered to an arbitrarily selected thread
 134 in the target process that is not blocking the signal.
 135 For more details, see
 136 .BR signal (7)
 137 and the description of
 138 .B CLONE_THREAD
 139 in
 140 .BR clone (2).
 141
 142 .SH RETURN CODES
 143 .B kill
 144 has the following return codes:
 145 .TP
 146 .B 0
 147 success
 148 .TP
 149 .B 1
 150 failure
 151 .TP
 152 .B 64
 153 partial success (when more than one process specified)
 154
 155 .SH SEE ALSO
 156 .BR bash (1),
 157 .BR tcsh (1),
 158 .BR sigaction (2),
 159 .BR kill (2),
 160 .BR sigqueue (3),
 161 .BR signal (7)
 162
 163 .SH AUTHORS
 164 .MT svalente@mit.edu
 165 Salvatore Valente
 166 .ME
 167 .br
 168 .MT kzak@redhat.com
 169 Karel Zak
 170 .ME
 171 .br
 172 .PP
 173 The original version was taken from BSD 4.4.
 174
 175 .SH AVAILABILITY
 176 The kill command is part of the util-linux package and is available from
 177 .UR https://\:www.kernel.org\:/pub\:/linux\:/utils\:/util-linux/
 178 Linux Kernel Archive
 179 .UE .