Open System Services Shell and Utilities Reference Manual (G06.25+, H06.03+)

User Commands (g - j) ipcs(1)
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 seg-
ment detaches it.
MODE (all)
The facility access modes and flags. The mode consists of 11 characters that are inter-
preted as follows. The first character is one of the following:
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 segment 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 characters 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 char-
acter 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.
w Write permission is granted (for shared memory segments).
a Alter permission is granted (for semaphore sets).
- The indicated permission is not granted.
OWNER (all)
The username of the owner of the facility entry.
GROUP (all)
The group name of the owner of the facility entry.
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