From Linux Man Pages
ipcrm - remove a message queue, semaphore set or shared memory id
SYNOPSIS
ipcrm [ -M key | -m id | -Q key | -q id | -S key | -s id ] ...
deprecated usage
ipcrm [ shm | msg | sem ] id ...
DESCRIPTION
ipcrm removes System V interprocess communication (IPC) objects and associated data structures from the system.
In order to delete such objects, you must be superuser, or the creator or owner of the object.
System V IPC objects are of three types: shared memory, message queues, and semaphores. Deletion of a message
queue or semaphore object is immediate (regardless of whether any process still holds an IPC identifier for the
object). A shared memory object is only removed after all currently attached processes have detached (shmdt(2))
the object from their virtual address space.
Two syntax styles are supported. The old Linux historical syntax specifies a three letter keyword indicating
which class of object is to be deleted, followed by one or more IPC identifiers for objects of this type.
The SUS-compliant syntax allows the specification of zero or more objects of all three types in a single command
line, with objects specified either by key or by identifier. (See below.) Both keys and identifiers may be spec-
ified in decimal, hexadecimal (specified with an initial '0x' or '0X'), or octal (specified with an initial '0').
OPTIONS
-M shmkey
removes the shared memory segment created with shmkey after the last detach is performed.
-m shmid
removes the shared memory segment identified by shmid after the last detach is performed.
-Q msgkey
removes the message queue created with msgkey.
-q msgid
removes the message queue identified by msgid.
-S semkey
removes the semaphore created with semkey.
-s semid
removes the semaphore identified by semid.
The details of the removes are described in msgctl(2), shmctl(2), and semctl(2). The identifiers and keys may be
found by using ipcs(8).
NOTES
In its first Linux implementation, ipcrm used the deprecated syntax shown in the SYNOPSIS. Functionality present
in other *nix implementations of ipcrm has since been added, namely the ability to delete resources by key (not
just identifier), and to respect the same command-line syntax. For backward compatibility the previous syntax is
still supported.
RELATED
ipcs(8), msgctl(2), msgget(2), semctl(2), semget(2), shmctl(2), shmdt(2), shmget(2), ftok(3)
CATEGORY