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NAME    [Toc]    [Back]

       signal - list of available signals

DESCRIPTION    [Toc]    [Back]

       Linux  supports	the  signals  listed below. Several signal numbers are
       architecture dependent. First the signals described in POSIX.1.

       Signal	  Value     Action   Comment
       SIGHUP	     1	      A      Hangup detected on controlling terminal
				     or death of controlling process
       SIGINT	     2	      A      Interrupt from keyboard
       SIGQUIT	     3	      C      Quit from keyboard
       SIGILL	     4	      C      Illegal Instruction
       SIGABRT	     6	      C      Abort signal from abort(3)
       SIGFPE	     8	      C      Floating point exception
       SIGKILL	     9	     AEF     Kill signal
       SIGSEGV	    11	      C      Invalid memory reference
       SIGPIPE	    13	      A      Broken pipe: write to pipe with no readers
       SIGALRM	    14	      A      Timer signal from alarm(2)
       SIGTERM	    15	      A      Termination signal
       SIGUSR1	 30,10,16     A      User-defined signal 1
       SIGUSR2	 31,12,17     A      User-defined signal 2
       SIGCHLD	 20,17,18     B      Child stopped or terminated
       SIGCONT	 19,18,25	     Continue if stopped
       SIGSTOP	 17,19,23    DEF     Stop process
       SIGTSTP	 18,20,24     D      Stop typed at tty
       SIGTTIN	 21,21,26     D      tty input for background process
       SIGTTOU	 22,22,27     D      tty output for background process

       Next the signals not in POSIX.1 but described in SUSv2.

       Signal	    Value     Action   Comment
       SIGBUS	   10,7,10	C      Bus error (bad memory access)
       SIGPOLL			A      Pollable event (Sys V). Synonym of SIGIO
       SIGPROF	   27,27,29	A      Profiling timer expired
       SIGSYS	   12,-,12	C      Bad argument to routine (SVID)
       SIGTRAP	      5 	C      Trace/breakpoint trap
       SIGURG	   16,23,21	B      Urgent condition on socket (4.2 BSD)
       SIGVTALRM   26,26,28	A      Virtual alarm clock (4.2 BSD)
       SIGXCPU	   24,24,30	C      CPU time limit exceeded (4.2 BSD)
       SIGXFSZ	   25,25,31	C      File size limit exceeded (4.2 BSD)

       (For the cases SIGSYS, SIGXCPU, SIGXFSZ, and on some architectures also
       SIGBUS,	the  Linux default action up to now (2.3.27) is A (terminate),
       while SUSv2 prescribes C (terminate and dump core).)

       Next various other signals.

       Signal	    Value     Action   Comment
       SIGIOT	      6 	C      IOT trap. A synonym for SIGABRT
       SIGEMT	    7,-,7
       SIGSTKFLT    -,16,-	A      Stack fault on coprocessor

       SIGIO	   23,29,22	A      I/O now possible (4.2 BSD)
       SIGCLD	    -,-,18	       A synonym for SIGCHLD
       SIGPWR	   29,30,19	A      Power failure (System V)
       SIGINFO	    29,-,-	       A synonym for SIGPWR
       SIGLOST	    -,-,-	A      File lock lost
       SIGWINCH    28,28,20	B      Window resize signal (4.3 BSD, Sun)
       SIGUNUSED    -,31,-	A      Unused signal (will be SIGSYS)

       (Here - denotes that a signal is absent; there where three  values  are
       given,  the  first one is usually valid for alpha and sparc, the middle
       one for i386 and ppc and sh, the last one for mips.  Signal 29 is  SIG-
       INFO / SIGPWR on an alpha but SIGLOST on a sparc.)

       The letters in the "Action" column have the following meanings:

       A      Default action is to terminate the process.

       B      Default action is to ignore the signal.

       C      Default action is to terminate the process and dump core.

       D      Default action is to stop the process.

       E      Signal cannot be caught.

       F      Signal cannot be ignored.

CONFORMING TO    [Toc]    [Back]


BUGS    [Toc]    [Back]

       SIGIO  and SIGLOST have the same value.	The latter is commented out in
       the kernel source, but the build process of some software still	thinks
       that signal 29 is SIGLOST.

SEE ALSO    [Toc]    [Back]

       kill(1), kill(2), setitimer(2)

Linux 1.3.88			  1996-04-14			     SIGNAL(7)
[ Back ]
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