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438 lines
9.4 KiB
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of SIGVEC</TITLE>
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</HEAD><BODY>
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<H1>SIGVEC</H1>
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Section: Linux Programmer's Manual (3)<BR>Updated: 2017-09-15<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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sigvec, sigblock, sigsetmask, siggetmask, sigmask - BSD signal API
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<B>#include <<A HREF="file:///usr/include/signal.h">signal.h</A>></B>
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<P>
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<B>int sigvec(int </B><I>sig</I><B>, const struct sigvec *</B><I>vec</I><B>, struct sigvec *</B><I>ovec</I><B>);</B>
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<P>
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<B>int sigmask(int </B><I>signum</I><B>);</B>
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<P>
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<B>int sigblock(int </B><I>mask</I><B>);</B>
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<P>
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<B>int sigsetmask(int </B><I>mask</I><B>);</B>
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<P>
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<B>int siggetmask(void);</B>
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<P>
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Feature Test Macro Requirements for glibc (see
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<B><A HREF="/cgi-bin/man/man2html?7+feature_test_macros">feature_test_macros</A></B>(7)):
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<P>
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All functions shown above:
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<BR> Since glibc 2.19:
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<BR> _DEFAULT_SOURCE
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<BR> Glibc 2.19 and earlier:
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<BR> _BSD_SOURCE
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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These functions are provided in glibc as a compatibility interface
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for programs that make use of the historical BSD signal API.
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This API is obsolete: new applications should use the POSIX signal API
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(<B><A HREF="/cgi-bin/man/man2html?2+sigaction">sigaction</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?2+sigprocmask">sigprocmask</A></B>(2),
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etc.).
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<P>
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The
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<B>sigvec</B>()
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function sets and/or gets the disposition of the signal
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<I>sig</I>
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(like the POSIX
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<B><A HREF="/cgi-bin/man/man2html?2+sigaction">sigaction</A></B>(2)).
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If
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<I>vec</I>
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is not NULL, it points to a
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<I>sigvec</I>
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structure that defines the new disposition for
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<I>sig</I>.
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If
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<I>ovec</I>
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is not NULL, it points to a
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<I>sigvec</I>
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structure that is used to return the previous disposition of
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<I>sig</I>.
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To obtain the current disposition of
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<I>sig</I>
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without changing it, specify NULL for
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<I>vec</I>,
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and a non-null pointer for
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<I>ovec</I>.
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<P>
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The dispositions for
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<B>SIGKILL</B>
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and
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<B>SIGSTOP</B>
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cannot be changed.
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<P>
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The
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<I>sigvec</I>
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structure has the following form:
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<P>
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struct sigvec {
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<BR> void (*sv_handler)(int); /* Signal disposition */
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<BR> int sv_mask; /* Signals to be blocked in handler */
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<BR> int sv_flags; /* Flags */
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};
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<P>
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The
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<I>sv_handler</I>
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field specifies the disposition of the signal, and is either:
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the address of a signal handler function;
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<B>SIG_DFL</B>,
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meaning the default disposition applies for the signal; or
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<B>SIG_IGN</B>,
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meaning that the signal is ignored.
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<P>
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If
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<I>sv_handler</I>
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specifies the address of a signal handler, then
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<I>sv_mask</I>
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specifies a mask of signals that are to be blocked while
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the handler is executing.
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In addition, the signal for which the handler is invoked is
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also blocked.
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Attempts to block
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<B>SIGKILL</B>
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or
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<B>SIGSTOP</B>
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are silently ignored.
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<P>
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If
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<I>sv_handler</I>
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specifies the address of a signal handler, then the
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<I>sv_flags</I>
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field specifies flags controlling what happens when the handler is called.
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This field may contain zero or more of the following flags:
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<DL COMPACT>
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<DT id="1"><B>SV_INTERRUPT</B>
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<DD>
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If the signal handler interrupts a blocking system call,
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then upon return from the handler the system call s not be restarted:
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instead it fails with the error
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<B>EINTR</B>.
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If this flag is not specified, then system calls are restarted
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by default.
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<DT id="2"><B>SV_RESETHAND</B>
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<DD>
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Reset the disposition of the signal to the default
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before calling the signal handler.
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If this flag is not specified, then the handler remains established
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until explicitly removed by a later call to
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<B>sigvec</B>()
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or until the process performs an
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<B><A HREF="/cgi-bin/man/man2html?2+execve">execve</A></B>(2).
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<DT id="3"><B>SV_ONSTACK</B>
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<DD>
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Handle the signal on the alternate signal stack
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(historically established under BSD using the obsolete
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<B>sigstack</B>()
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function; the POSIX replacement is
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<B><A HREF="/cgi-bin/man/man2html?2+sigaltstack">sigaltstack</A></B>(2)).
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</DL>
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<P>
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The
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<B>sigmask</B>()
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macro constructs and returns a "signal mask" for
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<I>signum</I>.
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For example, we can initialize the
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<I>vec.sv_mask</I>
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field given to
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<B>sigvec</B>()
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using code such as the following:
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<P>
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vec.sv_mask = sigmask(SIGQUIT) | sigmask(SIGABRT);
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<BR> /* Block SIGQUIT and SIGABRT during
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<BR> handler execution */
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<P>
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The
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<B>sigblock</B>()
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function adds the signals in
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<I>mask</I>
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to the process's signal mask
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(like POSIX
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<I>sigprocmask(SIG_BLOCK)</I>),
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and returns the process's previous signal mask.
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Attempts to block
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<B>SIGKILL</B>
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or
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<B>SIGSTOP</B>
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are silently ignored.
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<P>
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The
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<B>sigsetmask</B>()
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function sets the process's signal mask to the value given in
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<I>mask</I>
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(like POSIX
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<I>sigprocmask(SIG_SETMASK)</I>),
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and returns the process's previous signal mask.
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<P>
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The
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<B>siggetmask</B>()
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function returns the process's current signal mask.
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This call is equivalent to
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<I>sigblock(0)</I>.
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<A NAME="lbAE"> </A>
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<H2>RETURN VALUE</H2>
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The
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<B>sigvec</B>()
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function returns 0 on success; on error, it returns -1 and sets
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<I>errno</I>
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to indicate the error.
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<P>
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The
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<B>sigblock</B>()
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and
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<B>sigsetmask</B>()
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functions return the previous signal mask.
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<P>
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The
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<B>sigmask</B>()
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macro returns the signal mask for
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<I>signum</I>.
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<A NAME="lbAF"> </A>
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<H2>ERRORS</H2>
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See the ERRORS under
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<B><A HREF="/cgi-bin/man/man2html?2+sigaction">sigaction</A></B>(2)
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and
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<B><A HREF="/cgi-bin/man/man2html?2+sigprocmask">sigprocmask</A></B>(2).
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<A NAME="lbAG"> </A>
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<H2>VERSIONS</H2>
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Starting with version 2.21, the GNU C library no longer exports the
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<B>sigvec</B>()
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function as part of the ABI.
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(To ensure backward compatibility,
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the glibc symbol versioning scheme continues to export the interface
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to binaries linked against older versions of the library.)
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<A NAME="lbAH"> </A>
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<H2>ATTRIBUTES</H2>
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For an explanation of the terms used in this section, see
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<B><A HREF="/cgi-bin/man/man2html?7+attributes">attributes</A></B>(7).
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<TABLE BORDER>
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<TR VALIGN=top><TD><B>Interface</B></TD><TD><B>Attribute</B></TD><TD><B>Value</B><BR></TD></TR>
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<TR VALIGN=top><TD>
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<B>sigvec</B>(),
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<B>sigmask</B>(),
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<B>sigblock</B>(),
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<B>sigsetmask</B>(),
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<B>siggetmask</B>()
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</TD><TD>Thread safety</TD><TD>MT-Safe<BR></TD></TR>
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</TABLE>
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<A NAME="lbAI"> </A>
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<H2>CONFORMING TO</H2>
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All of these functions were in
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4.3BSD, except
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<B>siggetmask</B>(),
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whose origin is unclear.
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These functions are obsolete: do not use them in new programs.
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<A NAME="lbAJ"> </A>
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<H2>NOTES</H2>
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On 4.3BSD, the
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<B>signal</B>()
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function provided reliable semantics (as when calling
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<B>sigvec</B>()
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with
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<I>vec.sv_mask</I>
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equal to 0).
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On System V,
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<B>signal</B>()
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provides unreliable semantics.
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POSIX.1 leaves these aspects of
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<B>signal</B>()
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unspecified.
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See
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<B><A HREF="/cgi-bin/man/man2html?2+signal">signal</A></B>(2)
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for further details.
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<P>
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In order to wait for a signal,
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BSD and System V both provided a function named
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<B><A HREF="/cgi-bin/man/man2html?3+sigpause">sigpause</A></B>(3),
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but this function has a different argument on the two systems.
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See
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<B><A HREF="/cgi-bin/man/man2html?3+sigpause">sigpause</A></B>(3)
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for details.
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<A NAME="lbAK"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?2+kill">kill</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?2+pause">pause</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?2+sigaction">sigaction</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?2+signal">signal</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?2+sigprocmask">sigprocmask</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?3+raise">raise</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+sigpause">sigpause</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+sigset">sigset</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?7+signal">signal</A></B>(7)
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<A NAME="lbAL"> </A>
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<H2>COLOPHON</H2>
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This page is part of release 5.05 of the Linux
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<I>man-pages</I>
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project.
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A description of the project,
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information about reporting bugs,
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and the latest version of this page,
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can be found at
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<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="4"><A HREF="#lbAB">NAME</A><DD>
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<DT id="5"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="6"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="7"><A HREF="#lbAE">RETURN VALUE</A><DD>
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<DT id="8"><A HREF="#lbAF">ERRORS</A><DD>
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<DT id="9"><A HREF="#lbAG">VERSIONS</A><DD>
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<DT id="10"><A HREF="#lbAH">ATTRIBUTES</A><DD>
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<DT id="11"><A HREF="#lbAI">CONFORMING TO</A><DD>
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<DT id="12"><A HREF="#lbAJ">NOTES</A><DD>
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<DT id="13"><A HREF="#lbAK">SEE ALSO</A><DD>
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<DT id="14"><A HREF="#lbAL">COLOPHON</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:05:56 GMT, March 31, 2021
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</BODY>
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</HTML>
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