1SIGNAL(7)                  Linux Programmer's Manual                 SIGNAL(7)
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NAME

6       signal - overview of signals
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DESCRIPTION

9       Linux  supports both POSIX reliable signals (hereinafter "standard sig‐
10       nals") and POSIX real-time signals.
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12   Signal dispositions
13       Each signal has a current disposition, which determines how the process
14       behaves when it is delivered the signal.
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16       The  entries  in  the  "Action"  column  of the table below specify the
17       default disposition for each signal, as follows:
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19       Term   Default action is to terminate the process.
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21       Ign    Default action is to ignore the signal.
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23       Core   Default action is to terminate the process and  dump  core  (see
24              core(5)).
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26       Stop   Default action is to stop the process.
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28       Cont   Default  action  is  to  continue the process if it is currently
29              stopped.
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31       A process can change the disposition of a signal using sigaction(2)  or
32       signal(2).   (The  latter  is  less portable when establishing a signal
33       handler; see signal(2) for  details.)   Using  these  system  calls,  a
34       process  can  elect one of the following behaviors to occur on delivery
35       of the signal: perform the default action; ignore the signal; or  catch
36       the signal with a signal handler, a programmer-defined function that is
37       automatically invoked when the signal is delivered.
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39       By default, a signal handler is invoked on the  normal  process  stack.
40       It  is  possible  to  arrange that the signal handler uses an alternate
41       stack; see sigaltstack(2) for a discussion of how to do this  and  when
42       it might be useful.
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44       The  signal  disposition is a per-process attribute: in a multithreaded
45       application, the disposition of a particular signal is the same for all
46       threads.
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48       A child created via fork(2) inherits a copy of its parent's signal dis‐
49       positions.  During an execve(2), the dispositions  of  handled  signals
50       are  reset to the default; the dispositions of ignored signals are left
51       unchanged.
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53   Sending a signal
54       The following system calls and library functions allow  the  caller  to
55       send a signal:
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57       raise(3)        Sends a signal to the calling thread.
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59       kill(2)         Sends  a  signal to a specified process, to all members
60                       of a specified process group, or to  all  processes  on
61                       the system.
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63       killpg(3)       Sends  a  signal  to  all of the members of a specified
64                       process group.
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66       pthread_kill(3) Sends a signal to a specified POSIX thread in the  same
67                       process as the caller.
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69       tgkill(2)       Sends  a signal to a specified thread within a specific
70                       process.  (This is the system call  used  to  implement
71                       pthread_kill(3).)
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73       sigqueue(3)     Sends  a  real-time  signal with accompanying data to a
74                       specified process.
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76   Waiting