Content-type: text/html Man page of msgget

msgget

Section: System Calls (2)
Updated: 11 Feb 2003
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NAME

msgget - get message queue  

SYNOPSIS

#include <sys/msg.h>

int msgget(key_t key, int msgflg);  

DESCRIPTION

The msgget() argument returns the message queue identifier associated with key.

A message queue identifier and associated message queue and data structure (see intro(2)) are created for key if one of the following are true:

key is IPC_PRIVATE.

key does not already have a message queue identifier associated with it, and (msgflg&IPC_CREAT) is true.

On creation, the data structure associated with the new message queue identifier is initialized as follows:

msg_perm.cuid, msg_perm.uid, msg_perm.cgid, and msg_perm.gid are set to the effective user ID and effective group ID, respectively, of the calling process.

• The low-order 9 bits of msg_perm.mode are set to the low-order 9 bits of msgflg.

msg_qnum, msg_lspid, msg_lrpid, msg_stime, and msg_rtime are set to 0.

msg_ctime is set to the current time.

msg_qbytes is set to the system limit. See NOTES.

 

RETURN VALUES

Upon successful completion, a non-negative integer representing a message queue identifier is returned. Otherwise, -1 is returned and errno is set to indicate the error.  

ERRORS

The msgget() function will fail if:

EACCES A message queue identifier exists for key, but operation permission (see intro(2)) as specified by the low-order 9 bits of msgflg would not be granted.

EEXIST A message queue identifier exists for key but (msgflg&IPC_CREAT) and (msgflg&IPC_EXCL) are both true.

ENOENT A message queue identifier does not exist for key and (msgflg&IPC_CREAT) is false.

ENOSPC A message queue identifier is to be created but the system-imposed limit on the maximum number of allowed message queue identifiers system wide would be exceeded. See NOTES.

 

ATTRIBUTES

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPEATTRIBUTE VALUE
Interface StabilityStandard

 

SEE ALSO

rctladm(1M), intro(2), msgctl(2), msgrcv(2), msgsnd(2), setrctl(2), ftok(3C), attributes(5), standards(5)  

NOTES

The system-defined limit used to initialize msg_qbytes is the minimum enforced value of the calling process's process.max-msg-qbytes resource control.

The system-imposed limit on the number of message queue identifiers is maintained on a per-project basis using the project.max-msg-ids resource control.


 See rctladm(1M) and setrctl(2) for information about using resource controls.


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUES
ERRORS
ATTRIBUTES
SEE ALSO
NOTES

This document was created by man2html, using the manual pages.
Time: 02:37:16 GMT, October 02, 2010