IPCRM(1) User Commands IPCRM(1)
NAME
ipcrm - remove a message queue, semaphore set or shared memory id
SYNOPSIS
ipcrm [options]
ipcrm {shm|msg|sem} id...
DESCRIPTION
ipcrm removes System V interprocess communication (IPC) objects and associated data structures from the sys‐
tem. 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 com‐
mand line, with objects specified either by key or by identifier. (See below.) Both keys and identifiers may
be specified in decimal, hexadecimal (specified with an initial '0x' or '0X'), or octal (specified with an
initial '0').
OPTIONS
-M, --shmem-key shmkey
removes the shared memorysegment created with shmkey after the last detach is performed.
-m, --shmem-id shmid
removes the shared memory segment identified by shmid after the last detach is performed.
-Q, --queue-key msgkey
removes the message queue created with msgkey.
-q, --queue-id msgid
removes the message queue identified by msgid.
-S, --semaphore-key semkey
removes the semaphore created with semkey.
-s, --semaphore-id semid
removes the semaphore identified by semid.
-a, --all [shm msg sem]
Remove all resources. When option argument is provided the removal is performed only to for the speci‐
fied resource types. Warning! Do not use -a if you are unsure how the software using resources might
react on missing objects. Some programs create these resources at start up and may not have any code to
deal unexpected disappearance.
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(1).
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 previ‐
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