4.4BSD/usr/share/man/cat3f/signal.0

F>=1  .if 3F<=8 .    if 3F>1 .if 3F<6 .ds an-extra3 "BSD Program-



SIGNAL(3F)             BSD Reference Manual            SIGNAL(3F)

mer's Manual
NNAAMMEE
       signal - change the action for a signal

SSYYNNOOPPSSIISS
       iinntteeggeerr ffuunnccttiioonn ssiiggnnaall((ssiiggnnuumm,, pprroocc,, ffllaagg))
       iinntteeggeerr ssiiggnnuumm,, ffllaagg
       eexxtteerrnnaall pprroocc

DDEESSCCRRIIPPTTIIOONN
       When a  process  incurs  a  signal  (see  _s_i_g_n_a_l(3C))  the
       default action is usually to clean up and abort.  The user
       may choose to write an alternative  signal  handling  rou-
       tine.   A  call to _s_i_g_n_a_l is the way this alternate action
       is specified to the system.

       _S_i_g_n_u_m is the signal number (see _s_i_g_n_a_l(3C)).  If _f_l_a_g  is
       negative,  then  _p_r_o_c  must be the name of the user signal
       handling routine.  If _f_l_a_g is zero or positive, then  _p_r_o_c
       is  ignored  and the value of _f_l_a_g is passed to the system
       as the signal action definition.  In particular,  this  is
       how  previously saved signal actions can be restored.  Two
       possible values for _f_l_a_g have specific meanings:  0  means
       "use  the  default  action"  (See  NOTES  below),  1 means
       "ignore this signal".

       A positive returned value is the previous  action  defini-
       tion.   A value greater than 1 is the address of a routine
       that was to have been called on occurrence  of  the  given
       signal.   The  returned  value  can  be used in subsequent
       calls to _s_i_g_n_a_l in order to restore a previous action def-
       inition.   A  negative returned value is the negation of a
       system error code.  (See _p_e_r_r_o_r(3F))

FFIILLEESS
       /usr/lib/libU77.a

SSEEEE AALLSSOO
       signal(3C), kill(3F), kill(1)

NNOOTTEESS
       ff7777 arranges to trap certain signals  when  a  process  is
       started.   The  only way to restore the default ff7777 action
       is to save the returned value from the first call to  _s_i_g_-
       _n_a_l_.

       If  the  user  signal handler is called, it will be passed
       the signal number as an integer argument.






4.2 Berkeley Distribution  June 5, 1993                         1