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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-15 19:41:07 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-15 19:41:07 +0000
commit3af6d22bb3850ab2bac67287e3a3d3b0e32868e5 (patch)
tree3ee7a3ec64525911fa865bb984c86d997d855527 /man2/semctl.2
parentAdding debian version 6.05.01-1. (diff)
downloadmanpages-3af6d22bb3850ab2bac67287e3a3d3b0e32868e5.tar.xz
manpages-3af6d22bb3850ab2bac67287e3a3d3b0e32868e5.zip
Merging upstream version 6.7.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r--man2/semctl.262
1 files changed, 31 insertions, 31 deletions
diff --git a/man2/semctl.2 b/man2/semctl.2
index 6069169..c3724e4 100644
--- a/man2/semctl.2
+++ b/man2/semctl.2
@@ -20,7 +20,7 @@
.\" 2005-08-02, mtk: Added IPC_INFO, SEM_INFO, SEM_STAT descriptions.
.\" 2018-03-20, dbueso: Added SEM_STAT_ANY description.
.\"
-.TH semctl 2 2023-03-30 "Linux man-pages 6.05.01"
+.TH semctl 2 2024-03-03 "Linux man-pages 6.7"
.SH NAME
semctl \- System V semaphore control operations
.SH LIBRARY
@@ -29,26 +29,26 @@ Standard C library
.SH SYNOPSIS
.nf
.B #include <sys/sem.h>
-.PP
-.BI "int semctl(int " semid ", int " semnum ", int " cmd ", ...);"
+.P
+.BI "int semctl(int " semid ", int " semnum ", int " op ", ...);"
.fi
.SH DESCRIPTION
.BR semctl ()
performs the control operation specified by
-.I cmd
+.I op
on the System\ V semaphore set identified by
.IR semid ,
or on the
.IR semnum -th
semaphore of that set.
(The semaphores in a set are numbered starting at 0.)
-.PP
+.P
This function has three or four arguments, depending on
-.IR cmd .
+.IR op .
When there are four, the fourth has the type
.IR "union semun" .
The \fIcalling program\fP must define this union as follows:
-.PP
+.P
.in +4n
.EX
union semun {
@@ -60,11 +60,11 @@ union semun {
};
.EE
.in
-.PP
+.P
The
.I semid_ds
data structure is defined in \fI<sys/sem.h>\fP as follows:
-.PP
+.P
.in +4n
.EX
struct semid_ds {
@@ -76,7 +76,7 @@ struct semid_ds {
};
.EE
.in
-.PP
+.P
The fields of the
.I semid_ds
structure are as follows:
@@ -108,13 +108,13 @@ ranging from
.B 0
to
.IR sem_nsems\-1 .
-.PP
+.P
The
.I ipc_perm
structure is defined as follows
(the highlighted fields are settable using
.BR IPC_SET ):
-.PP
+.P
.in +4n
.EX
struct ipc_perm {
@@ -128,7 +128,7 @@ struct ipc_perm {
};
.EE
.in
-.PP
+.P
The least significant 9 bits of the
.I mode
field of the
@@ -144,12 +144,12 @@ l l.
0004 Read by others
0002 Write by others
.TE
-.PP
+.P
In effect, "write" means "alter" for a semaphore set.
Bits 0100, 0010, and 0001 (the execute bits) are unused by the system.
-.PP
+.P
Valid values for
-.I cmd
+.I op
are:
.TP
.B IPC_STAT
@@ -380,7 +380,7 @@ The calling process must have alter permission on the semaphore set.
On success,
.BR semctl ()
returns a nonnegative value depending on
-.I cmd
+.I op
as follows:
.TP
.B GETNCNT
@@ -420,11 +420,11 @@ the identifier of the semaphore set whose index was given in
.B SEM_STAT_ANY
as for
.BR SEM_STAT .
-.PP
+.P
All other
-.I cmd
+.I op
values return 0 on success.
-.PP
+.P
On failure,
.BR semctl ()
returns \-1 and sets
@@ -434,7 +434,7 @@ to indicate the error.
.TP
.B EACCES
The argument
-.I cmd
+.I op
has one of the values
.BR GETALL ,
.BR GETPID ,
@@ -464,7 +464,7 @@ The semaphore set was removed.
.TP
.B EINVAL
Invalid value for
-.I cmd
+.I op
or
.IR semid .
Or: for a
@@ -475,7 +475,7 @@ referred to an array slot that is currently unused.
.TP
.B EPERM
The argument
-.I cmd
+.I op
has the value
.B IPC_SET
or
@@ -493,7 +493,7 @@ capability.
.TP
.B ERANGE
The argument
-.I cmd
+.I op
has the value
.B SETALL
or
@@ -525,7 +525,7 @@ and explicitly notes that this value is set by a successful
call, with the implication that no other interface affects the
.I sempid
value.
-.PP
+.P
While some implementations conform to the behavior specified in POSIX.1,
others do not.
(The fault here probably lies with POSIX.1 inasmuch as it likely failed
@@ -543,7 +543,7 @@ on process termination as a consequence of the use of the
.B SEM_UNDO
flag (see
.BR semop (2)).
-.PP
+.P
Linux also updates
.I sempid
for
@@ -563,7 +563,7 @@ POSIX.1-2008.
.SH HISTORY
POSIX.1-2001, SVr4.
.\" SVr4 documents more error conditions EINVAL and EOVERFLOW.
-.PP
+.P
Various fields in a \fIstruct semid_ds\fP were typed as
.I short
under Linux 2.2
@@ -575,8 +575,8 @@ a recompilation under glibc-2.1.91 or later should suffice.
(The kernel distinguishes old and new calls by an
.B IPC_64
flag in
-.IR cmd .)
-.PP
+.IR op .)
+.P
In some earlier versions of glibc, the
.I semun
union was defined in \fI<sys/sem.h>\fP, but POSIX.1 requires
@@ -598,7 +598,7 @@ program to provide information on allocated resources.
In the future these may modified or moved to a
.I /proc
filesystem interface.
-.PP
+.P
The following system limit on semaphore sets affects a
.BR semctl ()
call:
@@ -607,7 +607,7 @@ call:
Maximum value for
.BR semval :
implementation dependent (32767).
-.PP
+.P
For greater portability, it is best to always call
.BR semctl ()
with four arguments.