From faeaa68ccafe51c6e27ae571a45bafe09ba8ee92 Mon Sep 17 00:00:00 2001 From: Michael Kerrisk Date: Thu, 29 Jan 2015 12:11:15 +0100 Subject: [PATCH] msgop.2: Clarify wording of MSGMAX and MSGMNB limits Signed-off-by: Michael Kerrisk --- man2/msgop.2 | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/man2/msgop.2 b/man2/msgop.2 index dad480719..e6d15bd41 100644 --- a/man2/msgop.2 +++ b/man2/msgop.2 @@ -517,23 +517,25 @@ The following limits on message queue resources affect the call: .TP .B MSGMAX -Maximum size for a message text: 8192 bytes -(on Linux, this limit can be read and modified via -.IR /proc/sys/kernel/msgmax ). +Maximum size of a message text, in bytes (default value: 8192 bytes). +On Linux, this limit can be read and modified via +.IR /proc/sys/kernel/msgmax . .TP .B MSGMNB -Default maximum size in bytes of a message queue: 16384 bytes -(on Linux, this limit can be read and modified via -.IR /proc/sys/kernel/msgmnb ). +Maximum number of bytes that can be held in a message queue +(default value: 16384 bytes). +On Linux, this limit can be read and modified via +.IR /proc/sys/kernel/msgmnb . A privileged process (Linux: a process with the .B CAP_SYS_RESOURCE capability) can increase the size of a message queue beyond .B MSGMNB -by a +using the .BR msgctl (2) -system call. +.B IPC_SET +operation. .PP The implementation has no intrinsic system-wide limits on the number of message headers