man2/tkill.2

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  24 .\" 2004-05-31, added tgkill, ahu, aeb
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  26 .TH TKILL 2 2007-06-01 "Linux" "Linux Programmer's Manual"
  27 .SH NAME
  28 tkill, tgkill \- send a signal to a single process
  29 .SH SYNOPSIS
  30 .nf
  31 .BI "int tkill(int " tid ", int " sig );
  32 .sp
  33 .BI "int tgkill(int " tgid ", int " tid ", int " sig );
  34 .fi
  35 .SH DESCRIPTION
  36 The
  37 .BR tkill ()
  38 system call is analogous to
  39 .BR kill (2),
  40 except when the specified process is part of a thread group
  41 (created by specifying the
  42 .B CLONE_THREAD
  43 flag in the call to
  44 .BR clone (2)).
  45 Since all the processes in a thread group have the same PID,
  46 they cannot be individually signaled with
  47 .BR kill (2).
  48 With
  49 .BR tkill (),
  50 however, one can address each process
  51 by its unique TID.
  52 .PP
  53 The
  54 .BR tgkill ()
  55 call improves on
  56 .BR tkill ()
  57 by allowing the caller to
  58 specify the thread group ID of the thread to be signaled, protecting
  59 against TID reuse.
  60 If the tgid is specified as \-1,
  61 .BR tgkill ()
  62 degenerates
  63 into
  64 .BR tkill ().
  65 .PP
  66 These are the raw system call interfaces, meant for internal
  67 thread library use.
  68 .SH "RETURN VALUE"
  69 On success, zero is returned.
  70 On error, \-1 is returned, and \fIerrno\fP
  71 is set appropriately.
  72 .SH ERRORS
  73 .TP
  74 .B EINVAL
  75 An invalid TID or signal was specified.
  76 .TP
  77 .B EPERM
  78 Permission denied.
  79 For the required permissions, see
  80 .BR kill (2).
  81 .TP
  82 .B ESRCH
  83 No process with the specified thread ID (and thread group ID) exists.
  84 .SH VERSIONS
  85 .BR tkill ()
  86 is supported since Linux 2.4.19 / 2.5.4.
  87 .BR tgkill ()
  88 was added in Linux 2.5.75.
  89 .SH "CONFORMING TO"
  90 .BR tkill ()
  91 and
  92 .BR tgkill ()
  93 are Linux-specific and should not be used
  94 in programs that are intended to be portable.
  95 .SH NOTES
  96 Glibc does not provide wrapper for these system calls; call them using
  97 .BR syscall (2).
  98 .SH "SEE ALSO"
  99 .BR gettid (2),
 100 .BR kill (2)