HP-UX Reference (11i v3 07/02) - 2 System Calls (vol 5)

shmctl(2) shmctl(2)

[EINVAL] shmid is not a valid shared memory identiﬁer.

[EINVAL] cmd is not a valid command, or the command contains invalid parameters.

[ENOMEM] cmd is equal to

SHM_LOCK and there is not sufﬁcient lockable memory to ﬁll the

request.

[EOVERFLOW]

cmd is equal to IPC_STAT . The attached process count of a shared memory object is

too large for the ﬁeld in the data structure provided by the application. Recompile the

application with the latest /usr/include/sys/ipc.h

ﬁle to resolve this issue.

[EPERM] cmd is equal to

IPC_RMID, IPC_SET

, SHM_LOCK,orSHM_UNLOCK and the

effective user ID of the calling process is not equal to that of a user having appropriate

privileges and it is not equal to the value of either

shm_perm.uid or

shm_perm.cuid in the data structure associated with shmid.

cmd is equal to

IPC_SET and the shared memory segment has

relaxed isola-

tion

[EPERM] cmd is equal to SHM_LOCK or SHM_UNLOCK and the effective user ID of the calling

process is not equal to that of a user having appropriate privileges and the calling pro-

cess does not have the

PRIV_MLOCK privilege (see getprivgrp(2)).

EXAMPLES

The following call to shmctl() locks in memory the shared memory segment represented by myshmid.

This example assumes the process has a valid shmid, which can be obtained by calling shmget(2).

shmctl (myshmid, SHM_LOCK, 0);

The following call to shmctl() removes the shared memory segment represented by myshmid. This

example assumes the process has a valid shmid, which can be obtained by calling shmget() (see

shmget(2).

shmctl (myshmid, IPC_RMID, 0);

AUTHOR

shmctl() was developed by AT&T and HP.