ipcs -- report interprocess communication facilities status:
system shared memory, message queues and semaphores

ipcrm 

 ipcs [-abcMmopQqSsTt]

 ipcs -asmq -tclup          ipcs [-s -m -q] -i id        ipcs -h for help.

The ipcs utility provides information on interprocess communication (IPC) facilities on the system.

Available   active
-M shared memory. -m
-Q messages queues. -q
-S semaphores. -s
-T Total (all) objects -o outstanding usage
-p process ID information for active objects. i.e.
  • is the last process to send a message to or receive a message from a message queue,
  • the process that created a semaphore, or
  • the last process to attach or detach a shared memory segment.
-c creator's name and group for active objects
-t times
    of the last control operation on an IPC object,
  • the last send or receive of a message,
  • the last attach or detach of a shared memory segment, or
  • the last operation on a semaphore.
-b maximums
the maximum number of bytes in a message on a message queue,
the size of a shared memory segment (in bytes)
the number of semaphores in a set of semaphores.
-a all information.
If none of the object options are specified, information about all active IPC facilities is listed.

RESTRICTIONS

System data structures may change while ipcs is running; the output of ipcs is not guaranteed to be consistent. SEE ALSO ipcrm 
 

usage : ipcs -asmq -tclup 
        ipcs [-s -m -q] -i id
        ipcs -h for help.


> ipcs -a
IPC status from  as of Thu Nov  5 15:04:43 EST 2009
T     ID     KEY        MODE   OWNER GROUP CREATOR CGROUP CBYTES  QNUM QBYTES LSPID LRPID STIME RTIME CTIME
Message Queues:

T     ID     KEY        MODE   OWNER GROUP CREATOR CGROUP NATTCH SEGSZ CPID LPID ATIME    DTIME    CTIME
Shared Memory:
m  65536 0x07021999 --rw-r--r-- root wheel   root  wheel      4  1460   191 343 17:37:03 15:02:36 17:34:06
m  65537 0x60022006 --rw-r--r-- root wheel   root  wheel      4    52   191 343 17:37:03 15:02:36 17:34:06

T     ID     KEY        MODE       OWNER    GROUP  CREATOR   CGROUP NSEMS   OTIME    CTIME
Semaphores:


 
> ipcs -M
IPC status from <running system> as of Thu Nov  5 15:05:29 EST 2009
shminfo:
        shmmax: 4194304 (max shared memory segment size)
        shmmin:       1 (min shared memory segment size)
        shmmni:      32 (max number of shared memory identifiers)
        shmseg:       8 (max shared memory segments per process)
        shmall:    1024 (max amount of shared memory in pages)

> ipcs -m 
------ Shared Memory Segments --------
key        shmid      owner      perms      bytes      nattch     status      
0x00000000 0          root      644        40         2                       
0x00000000 32769      root      644        16384      2                       
0x00000000 65538      root      644        268        2                       

 
> ipcs -q 
------ Message Queues --------
key        msqid      owner      perms      used-bytes   messages    


> ipcs -s 
------ Semaphore Arrays --------
key        semid      owner      perms      nsems     



 
> ipcs -t 
------ Shared Memory Attach/Detach/Change Times --------
shmid      owner      attached             detached             changed             
0          root        Sep  4 01:46:08      Sep  4 01:46:08      Sep  4 01:46:08     
32769      root        Sep  4 01:46:08      Sep  4 01:46:08      Sep  4 01:46:08     
65538      root        Sep  4 01:46:08      Sep  4 01:46:08      Sep  4 01:46:08     

------ Semaphore Operation/Change Times --------
semid    owner      last-op                    last-changed              

------ Message Queues Send/Recv/Change Times --------
msqid    owner      send                 recv                 change              



> ipcs -c
------ Shared Memory Segment Creators/Owners --------
shmid      perms      cuid       cgid       uid        gid       
0          644        root       root       root       root      
32769      644        root       root       root       root      
65538      644        root       root       root       root      

------ Semaphore Arrays Creators/Owners --------
semid      perms      cuid       cgid       uid        gid       

------ Message Queues: Creators/Owners --------
msqid      perms      cuid       cgid       uid        gid       

 




 > ipcs -usage
------ Shared Memory Status --------
segments allocated 4
pages allocated 16390
pages resident  8
pages swapped   0
Swap performance: 0 attempts 0 successes

------ Semaphore Status --------
used arrays = 5
allocated semaphores = 5




------ Messages: Status --------
allocated queues = 0
used headers = 0
used space = 0 bytes

 > ipcs -l 
------ Shared Memory Limits --------
max number of segments = 4096
max seg size (kbytes) = 4194303
max total shared memory (kb) = 1073741824
min seg size (bytes) = 1


------ Semaphore Limits --------
max number of arrays = 128
max semaphores per array = 250
max semaphores system wide = 32000
max ops per semop call = 32
semaphore max value = 32767

------ Messages: Limits --------
max queues system wide = 16
max size of message (bytes) = 65536
default max size of queue (bytes) = 65536

ipcrm - remove a message queue, semaphore set, or shared memory segment identifier

ipcrm [ -q msgid | -Q msgkey | -s semid | -S semkey | -m shmid | -M shmkey ] ...

-q msgID
-Q msgKey		 Remove the message queue its data.
-S semkey
-d semid 		Remove semaphore and its data.
-m shmid
-M shmkey 		Remove the shared memory identifier
The shared memory segment and its data are destroyed after the last detach.