man2/tkill.2

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  26 .\" 2004-05-31, added tgkill, ahu, aeb
  27 .\" 2008-01-15 mtk -- rewote DESCRIPTION
  28 .\"
  29 .TH TKILL 2 2011-09-18 "Linux" "Linux Programmer's Manual"
  30 .SH NAME
  31 tkill, tgkill \- send a signal to a thread
  32 .SH SYNOPSIS
  33 .nf
  34 .BI "int tkill(int " tid ", int " sig );
  35 .sp
  36 .BI "int tgkill(int " tgid ", int " tid ", int " sig );
  37 .fi
  38 .SH DESCRIPTION
  39 .BR tgkill ()
  40 sends the signal
  41 .I sig
  42 to the thread with the thread ID
  43 .I tid
  44 in the thread group
  45 .IR tgid .
  46 (By contrast,
  47 .BR kill (2)
  48 can only be used to send a signal to a process (i.e., thread group)
  49 as a whole, and the signal will be delivered to an arbitrary
  50 thread within that process.)
  51
  52 .BR tkill ()
  53 is an obsolete predecessor to
  54 .BR tgkill ().
  55 It only allows the target thread ID to be specified,
  56 which may result in the wrong thread being signaled if a thread
  57 terminates and its thread ID is recycled.
  58 Avoid using this system call.
  59
  60 If
  61 .I tgid
  62 is specified as \-1,
  63 .BR tgkill ()
  64 is equivalent to
  65 .BR tkill ().
  66
  67 These are the raw system call interfaces, meant for internal
  68 thread library use.
  69 .SH "RETURN VALUE"
  70 On success, zero is returned.
  71 On error, \-1 is returned, and \fIerrno\fP
  72 is set appropriately.
  73 .SH ERRORS
  74 .TP
  75 .B EINVAL
  76 An invalid thread ID, thread group ID, or signal was specified.
  77 .TP
  78 .B EPERM
  79 Permission denied.
  80 For the required permissions, see
  81 .BR kill (2).
  82 .TP
  83 .B ESRCH
  84 No process with the specified thread ID (and thread group ID) exists.
  85 .SH VERSIONS
  86 .BR tkill ()
  87 is supported since Linux 2.4.19 / 2.5.4.
  88 .BR tgkill ()
  89 was added in Linux 2.5.75.
  90 .SH "CONFORMING TO"
  91 .BR tkill ()
  92 and
  93 .BR tgkill ()
  94 are Linux-specific and should not be used
  95 in programs that are intended to be portable.
  96 .SH NOTES
  97 See the description of
  98 .B CLONE_THREAD
  99 in
 100 .BR clone (2)
 101 for an explanation of thread groups.
 102
 103 Glibc does not provide wrappers for these system calls; call them using
 104 .BR syscall (2).
 105 .SH "SEE ALSO"
 106 .BR clone (2),
 107 .BR gettid (2),
 108 .BR kill (2),
 109 .BR rt_sigqueueinfo (2)