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 .sp
  39 .B int tkill(int tid, int sig);
  40 .sp
  41 .B "_syscall3(int, tgkill, int, tgid, int, tid, int, sig)"
  42 .sp
  43 .B int tgkill(int tgid, int tid, int sig);
  44 .fi
  45 .SH DESCRIPTION
  46 The \fBtkill\fP() system call is analogous to
  47 .BR kill (2),
  48 except when the specified process is part of a thread group
  49 (created by specifying the CLONE_THREAD flag in the call to clone).
  50 Since all the processes in a thread group have the same PID,
  51 they cannot be individually signalled with \fBkill\fP().
  52 With \fBtkill\fP(), however, one can address each process
  53 by its unique TID.
  54 .PP
  55 The \fBtgkill\fP() call improves on \fBtkill\fP() by allowing the caller to
  56 specify the thread group ID of the thread to be signalled, protecting
  57 against TID reuse. If the tgid is specified as \-1, \fBtgkill\fP() degenerates
  58 into \fBtkill\fP().
  59 .PP
  60 These are the raw system call interfaces, meant for internal
  61 thread library use.
  62 .SH "RETURN VALUE"
  63 On success, zero is returned. On error, \-1 is returned, and \fIerrno\fP
  64 is set appropriately.
  65 .SH ERRORS
  66 .TP
  67 .B EINVAL
  68 An invalid TID or signal was specified.
  69 .TP
  70 .B EPERM
  71 Permission denied. For the required permissions, see
  72 .BR kill (2).
  73 .TP
  74 .B ESRCH
  75 No process with the specified thread ID (and thread group ID) exists.
  76 .SH "CONFORMING TO"
  77 \fBtkill\fP() and \fBtgkill\fP() are Linux specific and should not be used
  78 in programs that are intended to be portable.
  79 \fBtkill\fP() is supported since Linux 2.4.19 / 2.5.4.
  80 \fBtgkill\fP() was added in Linux 2.5.75.
  81 .SH "SEE ALSO"
  82 .BR gettid (2),
  83 .BR kill (2)