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semctl.2: Add information on permission bits (based on sysvipc(7) text) 

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
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Michael Kerrisk 2020-02-25 16:04:08 +01:00
parent c7d32a9ee7
commit 702f1a76e1
1 changed files with 19 additions and 0 deletions
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man2/semctl.2
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@ -142,6 +142,25 @@ struct ipc_perm {
.EE
.in
.PP
The least significant 9 bits of the
.I mode
field of the
.I ipc_perm
structure define the access permissions for the shared memory segment.
The permission bits are as follows:
.TS
l l.
0400 Read by user
0200 Write by user
0040 Read by group
0020 Write by group
0004 Read by others
0002 Write by others
.TE
.PP
In effect, "write" means "alter" for a semaphore set.
Bits 0100, 0010, and 0001 (the execute bits) are unused by the system.
.PP
Valid values for
.I cmd
are: