'\" t .\" Copyright (C) 2006 Michael Kerrisk .\" .\" SPDX-License-Identifier: Linux-man-pages-copyleft .\" .TH mq_close 3 2024-05-02 "Linux man-pages 6.8" .SH NAME mq_close \- close a message queue descriptor .SH LIBRARY Real-time library .RI ( librt ", " \-lrt ) .SH SYNOPSIS .nf .B #include .P .BI "int mq_close(mqd_t " mqdes ); .fi .SH DESCRIPTION .BR mq_close () closes the message queue descriptor .IR mqdes . .P If the calling process has attached a notification request (see .BR mq_notify (3)) to this message queue via .IR mqdes , then this request is removed, and another process can now attach a notification request. .SH RETURN VALUE On success .BR mq_close () returns 0; on error, \-1 is returned, with .I errno set to indicate the error. .SH ERRORS .TP .B EBADF The message queue descriptor specified in .I mqdes is invalid. .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 mq_close () T} Thread safety MT-Safe .TE .SH STANDARDS POSIX.1-2008. .SH HISTORY POSIX.1-2001. .SH NOTES All open message queues are automatically closed on process termination, or upon .BR execve (2). .SH SEE ALSO .BR mq_getattr (3), .BR mq_notify (3), .BR mq_open (3), .BR mq_receive (3), .BR mq_send (3), .BR mq_unlink (3), .BR mq_overview (7)