# Bash 的 ipcs 命令

ipcs [OPTIONS]

$ ipcs                      # 查看所有 IPC 资源

------ Message Queues --------
key        msqid      owner      perms      used-bytes   messages
0xb8bca3e8 0          primers    644        0            0

------ Shared Memory Segments --------
key        shmid      owner      perms      bytes      nattch     status
0xcbff4ae1 0          primers    644        256        0

------ Semaphore Arrays --------
key        semid      owner      perms      nsems
0x768e487c 0          primers    644        8

$ ipcs -l                   # 查看资源的限制

------ Messages Limits --------
max queues system wide = 32000
max size of message (bytes) = 8192
default max size of queue (bytes) = 16384

------ Shared Memory Limits --------
max number of segments = 4096
max seg size (kbytes) = 18014398509465599
max total shared memory (kbytes) = 18446744073709551612
min seg size (bytes) = 1

------ Semaphore Limits --------
max number of arrays = 32000
max semaphores per array = 32000
max semaphores system wide = 1024000000
max ops per semop call = 500
semaphore max value = 32767

$ ipcs -p                   # 查看资源的 PID

------ Message Queues PIDs --------
msqid      owner      lspid      lrpid
0          primers    0          0

------ Shared Memory Creator/Last-op PIDs --------
shmid      owner      cpid       lpid
0          planc      883345     0

IPCS(1)                          User Commands                         IPCS(1)

NAME
       ipcs - show information on IPC facilities

SYNOPSIS
       ipcs [options]

DESCRIPTION
       ipcs shows information on System V inter-process communication
       facilities. By default it shows information about all three resources:
       shared memory segments, message queues, and semaphore arrays.

OPTIONS
       -i, --id id
           Show full details on just the one resource element identified by
           id. This option needs to be combined with one of the three resource
           options: -m, -q or -s.

       -h, --help
           Display help text and exit.

       -V, --version
           Print version and exit.

   Resource options
       -m, --shmems
           Write information about active shared memory segments.

       -q, --queues
           Write information about active message queues.

       -s, --semaphores
           Write information about active semaphore sets.

       -a, --all
           Write information about all three resources (default).

   Output formats
       Of these options only one takes effect: the last one specified.

       -c, --creator
           Show creator and owner.

       -l, --limits
           Show resource limits.

       -p, --pid
           Show PIDs of creator and last operator.

       -t, --time
           Write time information. The time of the last control operation that
           changed the access permissions for all facilities, the time of the
           last msgsnd(2) and msgrcv(2) operations on message queues, the time
           of the last shmat(2) and shmdt(2) operations on shared memory, and
           the time of the last semop(2) operation on semaphores.

       -u, --summary
           Show status summary.

   Representation
       These affect only the -l (--limits) option.

       -b, --bytes
           Print the sizes in bytes rather than in a human-readable format.

           By default, the unit, sizes are expressed in, is byte, and unit
           prefixes are in power of 2^10 (1024). Abbreviations of symbols are
           exhibited truncated in order to reach a better readability, by
           exhibiting alone the first letter of them; examples: "1 KiB" and "1
           MiB" are respectively exhibited as "1 K" and "1 M", then omitting
           on purpose the mention "iB", which is part of these abbreviations.

       --human
           Print sizes in human-readable format.

CONFORMING TO
       The Linux ipcs utility is not fully compatible to the POSIX ipcs
       utility. The Linux version does not support the POSIX -a, -b and -o
       options, but does support the -l and -u options not defined by POSIX. A
       portable application shall not use the -a, -b, -o, -l, and -u options.

NOTES
       The current implementation of ipcs obtains information about available
       IPC resources by parsing the files in /proc/sysvipc. Before util-linux
       version v2.23, an alternate mechanism was used: the IPC_STAT command of
       msgctl(2), semctl(2), and shmctl(2). This mechanism is also used in
       later util-linux versions in the case where /proc is unavailable. A
       limitation of the IPC_STAT mechanism is that it can only be used to
       retrieve information about IPC resources for which the user has read
       permission.

AUTHORS
       Krishna Balasubramanian <[email protected]>

SEE ALSO
       ipcmk(1), ipcrm(1), msgrcv(2), msgsnd(2), semget(2), semop(2),
       shmat(2), shmdt(2), shmget(2), sysvipc(7)

REPORTING BUGS
       For bug reports, use the issue tracker at
       https://github.com/util-linux/util-linux/issues.

AVAILABILITY
       The ipcs command is part of the util-linux package which can be
       downloaded from Linux Kernel Archive
       <https://www.kernel.org/pub/linux/utils/util-linux/>.

util-linux 2.39.3                 2023-10-23                           IPCS(1)