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authorAlejandro Colomar <alx@kernel.org>2024-04-26 15:06:49 +0200
committerAlejandro Colomar <alx@kernel.org>2024-05-02 01:24:19 +0200
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tree78b9b7425130e4a5858e4c01a524d802423879ed /man/man3/sem_getvalue.3
parent12aca537ce78a41bbcdaf485209691e10f8002d7 (diff)
downloadman-pages-dcde2f70372b49ec43efc5db864c9ff585d0a2dd.tar.gz
man/, share/mk/: Move man*/ to man/
This is a scripted change: $ mkdir man/; $ mv man* man/; $ ln -st . man/man*; $ find share/mk/ -type f \ | xargs grep -l '^MANDIR *:=' \ | xargs sed -i '/^MANDIR *:=/s,$,/man,'; $ find share/mk/dist/ -type f \ | xargs grep -l man \ | xargs sed -i 's,man%,man/%,g'; Link: <https://lore.kernel.org/linux-man/YxcV4h+Xn7cd6+q2@pevik/T/> Cc: Petr Vorel <pvorel@suse.cz> Cc: Jakub Wilk <jwilk@jwilk.net> Cc: Stefan Puiu <stefan.puiu@gmail.com> Signed-off-by: Alejandro Colomar <alx@kernel.org>
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+'\" t
+.\" Copyright (C) 2006 Michael Kerrisk <mtk.manpages@gmail.com>
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.TH sem_getvalue 3 (date) "Linux man-pages (unreleased)"
+.SH NAME
+sem_getvalue \- get the value of a semaphore
+.SH LIBRARY
+POSIX threads library
+.RI ( libpthread ", " \-lpthread )
+.SH SYNOPSIS
+.nf
+.B #include <semaphore.h>
+.P
+.BI "int sem_getvalue(sem_t *restrict " sem ", int *restrict " sval );
+.fi
+.SH DESCRIPTION
+.BR sem_getvalue ()
+places the current value of the semaphore pointed to
+.I sem
+into the integer pointed to by
+.IR sval .
+.P
+If one or more processes or threads are blocked
+waiting to lock the semaphore with
+.BR sem_wait (3),
+POSIX.1 permits two possibilities for the value returned in
+.IR sval :
+either 0 is returned;
+or a negative number whose absolute value is the count
+of the number of processes and threads currently blocked in
+.BR sem_wait (3).
+Linux adopts the former behavior.
+.SH RETURN VALUE
+.BR sem_getvalue ()
+returns 0 on success;
+on error, \-1 is returned and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+.TP
+.B EINVAL
+.I sem
+is not a valid semaphore.
+(The glibc implementation currently does not check whether
+.I sem
+is valid.)
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface Attribute Value
+T{
+.na
+.nh
+.BR sem_getvalue ()
+T} Thread safety MT-Safe
+.TE
+.SH STANDARDS
+POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001.
+.SH NOTES
+The value of the semaphore may already have changed by the time
+.BR sem_getvalue ()
+returns.
+.SH SEE ALSO
+.BR sem_post (3),
+.BR sem_wait (3),
+.BR sem_overview (7)