NAME

       sighold, sigignore, sigpause, sigrelse, sigset — legacy interface for signal management

LIBRARY

       Standard C Library (libc, -lc)

SYNOPSIS

       #include <signal.h>

       int
       sighold(int sig);

       int
       sigignore(int sig);

       int
       xsi_sigpause(int sigmask);

       int
       sigrelse(int sig);

       void (*)(int)
       sigset(int, void (*disp)(int));

       int
       sigpause(int sigmask);

DESCRIPTION

       This interface is made obsolete by sigsuspend(2) and sigaction(2).

       The  sigset() function modifies signal dispositions.  The sig argument specifies the signal, which may be
       any signal except SIGKILL and SIGSTOP.  The disp argument specifies the signal's disposition,  which  may
       be SIG_DFL, SIG_IGN, or the address of a signal handler.  If sigset() is used, and disp is the address of
       a  signal  handler,  the  system  adds sig to the signal mask of the calling process before executing the
       signal handler; when the signal handler returns, the system restores  the  signal  mask  of  the  calling
       process  to its state prior to the delivery of the signal.  In addition, if sigset() is used, and disp is
       equal to SIG_HOLD, sig is added to the signal mask of the calling process and sig 's disposition  remains
       unchanged.   If  sigset() is used, and disp is not equal to SIG_HOLD, sig is removed from the signal mask
       of the calling process.

       The sighold() function adds sig to the signal mask of the calling process.

       The sigrelse() function removes sig from the signal mask of the calling process.

       The sigignore() function sets the disposition of sig to SIG_IGN.

       The xsi_sigpause() function removes sig from the signal mask of  the  calling  process  and  suspend  the
       calling  process until a signal is received.  The xsi_sigpause() function restores the signal mask of the
       process to its original state before returning.

       The sigpause() function assigns sigmask to the set of masked signals and  then  waits  for  a  signal  to
       arrive;  on  return the set of masked signals is restored.  The sigmask argument is usually 0 to indicate
       that no signals are to be blocked.

RETURN VALUES

       The sigpause() and xsi_sigpause() functions always terminate by  being  interrupted,  returning  -1  with
       errno set to EINTR.

       Upon  successful  completion,  sigset()  returns SIG_HOLD if the signal had been blocked and the signal's
       previous disposition if it had not been blocked.   Otherwise,  SIG_ERR  is  returned  and  errno  set  to
       indicate the error.

       For  all other functions, upon successful completion, 0 is returned.  Otherwise, -1 is returned and errno
       is set to indicate the error:

       [EINVAL]           The sig argument is not a valid signal number.

       [EINVAL]           For sigset() and sigignore() functions, an attempt was made to catch or ignore SIGKILL
                          or SIGSTOP.

SEE ALSO

       kill(2), sigaction(2), sigblock(2), sigprocmask(2), sigsuspend(2), sigvec(2)

STANDARDS

       The sigpause()  function  is  implemented  for  compatibility  with  historic  4.3BSD  applications.   An
       incompatible  interface  by  the  same  name,  which  used a single signal number rather than a mask, was
       present in AT&T System V UNIX, and was copied from there into the X/Open System Interfaces  (XSI)  option
       of  IEEE  Std  1003.1-2001  (“POSIX.1”).   FreeBSD  implements  it  under  the  name xsi_sigpause().  The
       sighold(), sigignore(), sigrelse() and sigset() functions are implemented for compatibility with System V
       and XSI interfaces.

HISTORY

       The sigpause() function appeared in 4.2BSD and has been deprecated.   All  other  functions  appeared  in
       FreeBSD 8.1 and were deprecated before being implemented.

Debian                                            June 2, 1993                                       SIGPAUSE(2)