NAME

sys/ipc.h — XSI interprocess communication access structure

SYNOPSIS

^[XSI] #include <sys/ipc.h>

DESCRIPTION

The <sys/ipc.h> header is used by three mechanisms for XSI interprocess communication (IPC): messages, semaphores, and shared memory. All use a common structure type, ipc_perm, to pass information used in determining permission to perform an IPC operation.

The <sys/ipc.h> header shall define the ipc_perm structure, which shall include the following members:

uid_t    uid    Owner's user ID.
gid_t    gid    Owner's group ID.
uid_t    cuid   Creator's user ID.
gid_t    cgid   Creator's group ID.
mode_t   mode   Read/write permission.

The <sys/ipc.h> header shall define the uid_t, gid_t, mode_t, and key_t types as described in <sys/types.h>.

The <sys/ipc.h> header shall define the following symbolic constants.

Mode bits:

IPC_CREAT

Create entry if key does not exist.

IPC_EXCL

Fail if key exists.

IPC_NOWAIT

Error if request would need to wait.

Keys:

IPC_PRIVATE

Private key.

Control commands:

IPC_RMID

Remove identifier.

IPC_SET

Set options.

IPC_STAT

Get options.

The following shall be declared as a function and may also be defined as a macro. A function prototype shall be provided.

key_t  ftok(const char *, int);

APPLICATION USAGE

None.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

<sys/types.h>

XSH ftok

CHANGE HISTORY

First released in Issue 2. Derived from System V Release 2.0.

Issue 7

This reference page is clarified with respect to macros and symbolic constants.

Issue 8

The description of IPC_NOWAIT is updated to eliminate the use of "must".