The Open Group Base Specifications Issue 8
IEEE Std 1003.1-2024
Copyright © 2001-2024 The IEEE and The Open Group

NAME

sys/ipc.h — XSI interprocess communication access structure

SYNOPSIS

[XSI] [Option Start] #include <sys/ipc.h> [Option End]

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);

The following sections are informative.

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".

End of informative text.

 

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