man2/tkill.2

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   3 .\" Copyright 2003 Abhijit Menon-Sen <ams@wiw.org>
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  24 .\" 2004-05-31, added tgkill, ahu, aeb
  25 .\"
  26 .TH TKILL 2 "2004-05-31" "Linux 2.6.6" "Linux Programmer's Manual"
  27 .SH NAME
  28 tkill, tgkill \- send a signal to a single process
  29 .SH SYNOPSIS
  30 .nf
  31 .B #include <sys/types.h>
  32 .br
  33 .B #include <linux/unistd.h>
  34 .br
  35 .B #include <errno.h>
  36 .sp
  37 .B "_syscall2(int, tkill, int, tid, int, sig)"
  38           /* Using \fBsyscall\fP(2) may be preferable; see \fBintro\fP(2) */
  39 .sp
  40 .B int tkill(int tid, int sig);
  41 .sp
  42 .B "_syscall3(int, tgkill, int, tgid, int, tid, int, sig)"
  43           /* Using \fBsyscall\fP(2) may be preferable; see \fBintro\fP(2) */
  44 .sp
  45 .B int tgkill(int tgid, int tid, int sig);
  46 .fi
  47 .SH DESCRIPTION
  48 The \fBtkill\fP() system call is analogous to
  49 .BR kill (2),
  50 except when the specified process is part of a thread group
  51 (created by specifying the CLONE_THREAD flag in the call to clone).
  52 Since all the processes in a thread group have the same PID,
  53 they cannot be individually signalled with \fBkill\fP().
  54 With \fBtkill\fP(), however, one can address each process
  55 by its unique TID.
  56 .PP
  57 The \fBtgkill\fP() call improves on \fBtkill\fP() by allowing the caller to
  58 specify the thread group ID of the thread to be signalled, protecting
  59 against TID reuse.
  60 If the tgid is specified as \-1, \fBtgkill\fP() degenerates
  61 into \fBtkill\fP().
  62 .PP
  63 These are the raw system call interfaces, meant for internal
  64 thread library use.
  65 .SH "RETURN VALUE"
  66 On success, zero is returned.
  67 On error, \-1 is returned, and \fIerrno\fP
  68 is set appropriately.
  69 .SH ERRORS
  70 .TP
  71 .B EINVAL
  72 An invalid TID or signal was specified.
  73 .TP
  74 .B EPERM
  75 Permission denied.
  76 For the required permissions, see
  77 .BR kill (2).
  78 .TP
  79 .B ESRCH
  80 No process with the specified thread ID (and thread group ID) exists.
  81 .SH "CONFORMING TO"
  82 \fBtkill\fP() and \fBtgkill\fP() are Linux specific and should not be used
  83 in programs that are intended to be portable.
  84 .SH VERSIONS
  85 \fBtkill\fP() is supported since Linux 2.4.19 / 2.5.4.
  86 \fBtgkill\fP() was added in Linux 2.5.75.
  87 .SH "SEE ALSO"
  88 .BR gettid (2),
  89 .BR kill (2)