2005-09-15 11:48:46 +00:00
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.\" Copyright (c) 2005 Michael Kerrisk
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.\" based on earlier work by faith@cs.unc.edu and
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.\" Mike Battersby <mib@deakin.edu.au>
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\"
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.\" 2005-09-15, mtk, Created new page by splitting off from sigaction.2
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.\"
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.TH SIGPROCMASK 2 2005-09-15 "Linux 2.6.13" "Linux Programmer's Manual"
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.SH NAME
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sigprocmask \- examine and change blocked signals
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.SH SYNOPSIS
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.B #include <signal.h>
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.sp
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.BI "int sigprocmask(int " how ", const sigset_t *" set ,
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.BI "sigset_t *" oldset );
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.SH DESCRIPTION
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.BR sigprocmask ()
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is used to change the signal mask, the set of currently blocked signals.
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The behaviour of the call is dependent on the value of
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.IR how ,
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as follows.
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.RS
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.TP
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.B SIG_BLOCK
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The set of blocked signals is the union of the current set and the
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.I set
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argument.
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.TP
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.B SIG_UNBLOCK
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The signals in
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.I set
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are removed from the current set of blocked signals. It is legal to
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attempt to unblock a signal which is not blocked.
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.TP
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.B SIG_SETMASK
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The set of blocked signals is set to the argument
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.IR set .
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.RE
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.PP
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If
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.I oldset
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is non\-null, the previous value of the signal mask is stored in
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.IR oldset .
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If
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.I set
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is NULL, then the signal mask is unchanged (i.e.,
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.I how
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is ignored),
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but the current value of the signal mask is nevertheless returned in
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.IR oldset
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2006-07-05 09:37:54 +00:00
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(it is not NULL).
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2005-09-15 11:48:46 +00:00
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The use of
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.BR sigprocmask ()
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is unspecified in a multithreaded process; see
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.BR pthread_sigmask (3).
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.SH "RETURN VALUE"
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.BR sigprocmask ()
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returns 0 on success and \-1 on error.
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.SH ERRORS
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.B EINVAL
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The value specified in
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.I how
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was invalid.
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.SH NOTES
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It is not possible to block
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.BR SIGKILL " or " SIGSTOP .
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Attempts to do so are silently ignored.
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.PP
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If
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.BR SIGBUS ,
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.BR SIGFPE ,
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.BR SIGILL ,
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or
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.BR SIGSEGV
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are generated
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while they are blocked, the result is undefined,
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unless the signal was generated by the
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.BR kill (2),
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.BR sigqueue (2),
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or
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.BR raise (3).
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.PP
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See
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.BR sigsetops (3)
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for details on manipulating signal sets.
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.SH "CONFORMING TO"
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POSIX.1-2001.
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.SH "SEE ALSO"
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.BR kill (2),
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.BR pause (2),
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.BR sigaction (2),
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.BR signal (2),
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.BR sigpending (2),
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.BR sigprocmask (2),
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.BR sigqueue (2),
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.BR sigsuspend (2),
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.BR pthread_sigmask (3),
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.BR sigsetops (3),
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.BR signal (7)
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