Open System Services Shell and Utilities Reference Manual (G06.29+, H06.08+, J06.03+)
User Commands (g - j) ipcs(1)
DESCRIPTION
The ipcs command writes information to the standard output file about active interprocess com-
munication (IPC) facilities on the processor in which the command runs. If you do not specify
any flags, ipcs writes information in short form about the currently active message queues, shared
memory segments, semaphore sets, and local message queue headers.
Column Headings
The column headings and the meanings of the columns in an ipcs listing follow. The letters in
parentheses indicate the flags that cause the corresponding heading to appear. The word "all"
means that the heading always appears. The flags determine only what information is provided
for each facility; they do not determine which facilities are listed.
T (all) Type of facility:
q Message queue
m Shared memory segment
s Semaphore
ID (all) The identifier for the facility entry.
KEY (all)
The key used as a parameter in the msgget(), semget(),orshmget()
function call that created the facility entry.
Note that the key of a shared memory segment is changed to
IPC__PRIVATE when the segment is removed. The entry disappears
when the last process attached to the segment detaches it.
MODE (all)
The facility access modes and flags. The mode consists of 11 charac-
ters that are interpreted as follows. The first character is one of the fol-
lowing:
R If a process is waiting on a msgrcv() function call.
S If a process is waiting on a msgsnd() function call.
D The associated shared memory segment was removed. The
entry disappears when the last process attached to the seg-
ment detaches it.
- The corresponding special flag is not set.
The second character is reserved for future use.
The next nine characters are interpreted as three sets of three charac-
ters each. The first set refers to the owner’s permissions; the second
set to permissions of others in the user group of the facility entry; and
the third set to all others. Within each set, the first character indicates
permission to read, the second character indicates permission to write
or alter the facility entry, and the last character is currently unused.
The permissions are indicated as follows:
r Read permission is granted.
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