mirror of https://github.com/mkerrisk/man-pages
132 lines
3.2 KiB
Plaintext
132 lines
3.2 KiB
Plaintext
.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
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.TH "<sys/sem.h>" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
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.\" <sys/sem.h>
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.SH NAME
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sys/sem.h \- XSI semaphore facility
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.SH SYNOPSIS
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.LP
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\fB#include <sys/sem.h> \fP
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.SH DESCRIPTION
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.LP
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The \fI<sys/sem.h>\fP header shall define the following constants
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and structures.
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.LP
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Semaphore operation flags:
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.TP 7
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SEM_UNDO
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Set up adjust on exit entry.
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.sp
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.LP
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Command definitions for the \fIsemctl\fP() function shall be provided
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as follows:
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.TP 7
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GETNCNT
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Get \fIsemncnt\fP.
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.TP 7
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GETPID
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Get \fIsempid\fP.
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.TP 7
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GETVAL
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Get \fIsemval\fP.
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.TP 7
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GETALL
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Get all cases of \fIsemval\fP.
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.TP 7
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GETZCNT
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Get \fIsemzcnt\fP.
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.TP 7
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SETVAL
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Set \fIsemval\fP.
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.TP 7
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SETALL
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Set all cases of \fIsemval\fP.
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.sp
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.LP
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The \fBsemid_ds\fP structure shall contain the following members:
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.sp
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.RS
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.nf
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\fBstruct ipc_perm sem_perm \fP Operation permission structure. \fB
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unsigned short sem_nsems\fP Number of semaphores in set. \fB
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time_t sem_otime\fP Last \fIsemop\fP
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() time. \fB
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time_t sem_ctime\fP Last time changed by \fIsemctl\fP
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(). \fB
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\fP
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.fi
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.RE
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.LP
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The \fBpid_t\fP, \fBtime_t\fP, \fBkey_t\fP, and \fBsize_t\fP types
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shall be defined as described in \fI<sys/types.h>\fP .
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.LP
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A semaphore shall be represented by an anonymous structure containing
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the following members:
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.sp
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.RS
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.nf
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\fBunsigned short semval \fP Semaphore value. \fB
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pid_t sempid \fP Process ID of last operation. \fB
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unsigned short semncnt \fP Number of processes waiting for \fIsemval\fP \fB
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\fP to become greater than current value. \fB
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unsigned short semzcnt \fP Number of processes waiting for \fIsemval\fP \fB
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\fP to become 0. \fB
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\fP
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.fi
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.RE
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.LP
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The \fBsembuf\fP structure shall contain the following members:
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.sp
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.RS
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.nf
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\fBunsigned short sem_num \fP Semaphore number. \fB
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short sem_op \fP Semaphore operation. \fB
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short sem_flg \fP Operation flags. \fB
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\fP
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.fi
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.RE
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.LP
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The following shall be declared as functions and may also be defined
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as macros. Function prototypes shall be provided.
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.sp
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.RS
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.nf
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\fBint semctl(int, int, int, ...);
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int semget(key_t, int, int);
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int semop(int, struct sembuf *, size_t);
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\fP
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.fi
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.RE
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.LP
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In addition, all of the symbols from \fI<sys/ipc.h>\fP shall be defined
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when
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this header is included.
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.LP
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\fIThe following sections are informative.\fP
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.SH APPLICATION USAGE
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.LP
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None.
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.SH RATIONALE
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.LP
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None.
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.SH FUTURE DIRECTIONS
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.LP
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None.
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.SH SEE ALSO
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.LP
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\fI<sys/ipc.h>\fP , \fI<sys/types.h>\fP , \fIsemctl\fP(), \fIsemget\fP(),
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\fIsemop\fP()
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.SH COPYRIGHT
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Portions of this text are reprinted and reproduced in electronic form
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from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
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-- Portable Operating System Interface (POSIX), The Open Group Base
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Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
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Electrical and Electronics Engineers, Inc and The Open Group. In the
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event of any discrepancy between this version and the original IEEE and
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The Open Group Standard, the original IEEE and The Open Group Standard
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is the referee document. The original Standard can be obtained online at
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http://www.opengroup.org/unix/online.html .
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