ipcs(1) User Commands ipcs(1)
ipcs - report inter-process communication facilities status
ipcs [-aAbciJmopqstZ] [-D mtype] [-z zone]
The ipcs utility prints information about active inter-process communi-
cation facilities. The information that is displayed is controlled by
the options supplied. Without options, information is printed in short
format for message queues, shared memory, and semaphores that are cur-
rently active in the system.
The following options are supported:
-m Prints information about active shared memory segments.
-q Prints information about active message queues.
-s Prints information about active semaphores.
If -m, -q, or -s are specified, information about only those indicated
is printed. If none of these three is specified, information about all
three is printed subject to these options:
-a Uses all XCU5 print options. (This is a shorthand nota-
tion for -b, -c, -o, -p, and -t.)
-A Uses all print options. (This is a shorthand notation
for -b, -c, -i, -J, -o, -p, and -t.)
-b Prints information on biggest allowable size: maximum
number of bytes in messages on queue for message
queues, size of segments for shared memory, and number
of semaphores in each set for semaphores. See below for
meaning of columns in a listing.
-c Prints creator's login name and group name. See below.
-D mtype Displays, in hexadecimal and ASCII, the contents of all
messages of type mtype found on any message queue that
the user invoking ipcs has permission to read. If mtype
is 0, all messages are displayed. If mtype is negative,
all messages with type less than or equal to the abso-
lute value of mtype are displayed. (See msgrcv(2) and
-i Prints number of ISM attaches to shared memory seg-
-J Prints the creator's project.
-o Prints information on outstanding usage: number of mes-
sages on queue and total number of bytes in messages on
queue for message queues and number of processes
attached to shared memory segments.
-p Prints process number information: process ID of last
process to send a message, process ID of last process
to receive a message on message queues, process ID of
creating process, and process ID of last process to
attach or detach on shared memory segments. See below.
-t Prints time information: time of the last control oper-
ation that changed the access permissions for all
facilities, time of last msgsnd(2) and last msgrcv(2)
on message queues, time of last shmat(2) and last
shmdt(2 ) on shared memory (see shmop(2)), time of last
semop(2) on semaphores. See below.
-z zone Prints information about facilities associated with the
specified zone (see zones(5)). The zone can be speci-
fied as either a name or a numeric id. The default is
to display information about the zone in which the com-
mand is executing. Notice that this option is only use-
ful when executing in the global zone.
-Z When executing in the global zone, prints information
about all zones. Otherwise, prints information about
the zone in which the command is executing. The output
includes the zone associated with each facility.
The column headings and the meaning of the columns in an ipcs listing
are given below. The letters in parentheses indicate the options that
cause the corresponding heading to appear and "all" means that the
heading always appears. Note: These options only determine what infor-
mation is provided for each facility; they do not determine which
facilities are listed.
T (all) Type of the facility:
q message queue
m shared memory segment
ID (all) The identifier for the facility entry.
KEY (all) The key used as an argument to msgget(2),
semget(2), or shmget(2) to create the facility
entry. (Note: The key of a shared memory seg-
ment is changed to IPC_PRIVATE when the segment
has been removed until all processes attached
to the segment detach it.)
MODE (all) The facility access modes and flags: The mode
consists of 11 characters that are interpreted
as follows. The first two characters are:
R A process is waiting on a msgrcv(2).
S A process is waiting on a msgsnd(2).
D The associated shared memory segment
has been removed. It will disappear
when the last process attached to the
segment detaches it. (Note: If the
shared memory segment identifier is
removed via an IPC_RMID call to shm-
ctl(2) before the process has detached
from the segment with shmdt(2), the
segment is no longer visible to ipcs
and it will not appear in the ipcs
C The associated shared memory segment
is to be cleared when the first attach
- The corresponding special flag is not
The next nine characters are interpreted as
three sets of three bits each. The first set
refers to the owner's permissions; the next to
permissions of others in the user-group of the
facility entry; and the last to all others.
Within each set, the first character indicates
permission to read, the second character indi-
cates permission to write or alter the facility
entry, and the last character is currently
The permissions are indicated as follows:
r Read permission is granted.
w Write permission is granted.
a Alter permission is granted.
- The indicated permission is not
OWNER (all) The login name of the owner of the facility
GROUP (all) The group name of the group of the owner of the
CREATOR (a,A,c) The login name of the creator of the facility
CGROUP (a,A,c) The group name of the group of the creator of
the facility entry.
CBYTES (a,A,o) The number of bytes in messages currently out-
standing on the associated message queue.
QNUM (a,A,o) The number of messages currently outstanding on
the associated message queue.
QBYTES (a,A,b) The maximum number of bytes allowed in messages
outstanding on the associated message queue.
LSPID (a,A,p) The process ID of the last process to send a
message to the associated queue.
LRPID (a,A,p) The process ID of the last process to receive a
message from the associated queue.
STIME (a,A,t) The time the last message was sent to the asso-
RTIME (a,A,t) The time the last message was received from the
CTIME (a,A,t) The time when the associated entry was created
ISMATTCH (a,i) The number of ISM attaches to the associated
shared memory segments.
NATTCH (a,A,o) The number of processes attached to the associ-
ated shared memory segment.
SEGSZ (a,A,b) The size of the associated shared memory seg-
CPID (a,A,p) The process ID of the creator of the shared
LPID (a,A,p) The process ID of the last process to attach or
detach the shared memory segment.
ATIME (a,A,t) The time the last attach was completed to the
associated shared memory segment.
DTIME (a,A,t) The time the last detach was completed on the
associated shared memory segment.
NSEMS (a,A,b) The number of semaphores in the set associated
with the semaphore entry.
OTIME (a,A,t) The time the last semaphore operation was com-
pleted on the set associated with the semaphore
PROJECT (J,A) The project name of the creator of the facility
ZONE (Z) The zone with which the facility is associated.
See environ(5) for descriptions of the following environment variables
that affect the execution of ipcs: LANG, LC_ALL, LC_CTYPE, LC_MES-
SAGES, and NLSPATH.
TZ Determine the timezone for the time strings written by ipcs.
/etc/group group names
/etc/passwd user names
See attributes(5) for descriptions of the following attributes:
tab() allbox; cw(2.750000i)| cw(2.750000i) lw(2.750000i)|
lw(2.750000i). ATTRIBUTE TYPEATTRIBUTE VALUE AvailabilitySUNWipc
ipcrm(1), msgget(2), msgids(2), msgrcv(2), msgsnap(2), msgsnd(2),
semget(2), semids(2), semop(2), shmctl(2), shmget(2), shmids(2),
shmop(2), attributes(5), environ( 5), standards(5), zones(5)
Things can change while ipcs is running. The information it gives is
guaranteed to be accurate only when it was retrieved.
SunOS 5.10 9 Jan 2004 ipcs(1)