NAME
mesg — enable or disable System V IPC messages at boot time
VALUES
Allowed values
1 (on)
or
0 (off)
DESCRIPTION
The
mesg
tunable is a "switch" designed to enable the entire System V IPC
message subsystem.
When disabled, kernel memory space for the facility will
not
be reserved on system boot, and the System V messaging system will be
totally removed.
Since some system daemons require use of these message queues,
a disabled message queue system will be the exception.
Overview
A System V message is just a sequence of bytes that can be passed
between cooperating processes via a message queue.
Messages can be of any length (up to a tunable maximum) and are
stored in one or more contiguous "segments" of reserved kernel memory
(managed through the message segment map).
Each message is "typed" with an application-specific number.
Each message queue is referenced by a unique ID, and can contain
multiple individual messages.
The process receiving a message can get the "first" message (FIFO),
the first of a specified type, the first of a group of types, or wait
for a specific type to appear.
Who Is Expected to Change This Tunable?
Anyone.
Restrictions on Changing
Changes to this tunable take effect at the next reboot.
What Are the Side Effects of Turning the Tunable Off?
Memory space will
not
be reserved on system boot, and the System V messaging system will
be totally removed.
As some system daemons may require use of these message queues, turning
this tunable off may cause some other system services to be unavailable.
What Other Tunable Values Should Be Changed at the Same Time?
All the System V IPC Message subsystem tunables are interrelated
and should
not
be treated as independent variables.
The set of eight tunables must be evaluated as a system to ensure they
reflect the application requirements.
The
mesg
tunables include
msgmap,
msgmax,
msgmnb,
msgmni,
msgseg,
msgssz,
and
msgtql.
WARNINGS
All HP-UX kernel tunable parameters are release specific.
This parameter may be removed or have its meaning changed in
future releases of HP-UX.
AUTHOR
mesg
was developed by AT&T.
SEE ALSO
ipcrm(1),
ipcs(1),
msgctl(2),
msgget(2),
msgrcv(2),
msgsnd(2),
msgmap(5),
msgmax(5),
msgmnb(5),
msgmni(5),
msgseg(5),
msgssz(5),
msgtql(5).
Printable version
