From 785008cd99f84260e34e9a3d6c43d3b780a63ec0 Mon Sep 17 00:00:00 2001 From: Michael Kerrisk Date: Sat, 6 Feb 2016 15:19:39 +0100 Subject: [PATCH] mq_overview.7: Note that the close-on-exec flag is automatically set on MQ descriptors Signed-off-by: Michael Kerrisk --- man7/mq_overview.7 | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/man7/mq_overview.7 b/man7/mq_overview.7 index a1fbff343..3655ca44e 100644 --- a/man7/mq_overview.7 +++ b/man7/mq_overview.7 @@ -336,14 +336,20 @@ and .B SIGNO Signal number to be used for .BR SIGEV_SIGNAL . -.SS Polling message queue descriptors -On Linux, a message queue descriptor is actually a file descriptor, -and can be monitored using +.SS Linux implementation of message queue descriptors +On Linux, a message queue descriptor is actually a file descriptor. +(POSIX does not require such an implementation.) +This means that a message queue descriptor can be monitored using .BR select (2), .BR poll (2), or .BR epoll (7). This is not portable. + +The close-on-exec flag (see +.BR open (2)) +is automatically set on the file descriptor returned by +.BR mq_open (2). .SS IPC namespaces For a discussion of the interaction of System V IPC objects and IPC namespaces, see