diff options
Diffstat (limited to 'man2/shmctl.2')
| -rw-r--r-- | man2/shmctl.2 | 48 |
1 files changed, 26 insertions, 22 deletions
diff --git a/man2/shmctl.2 b/man2/shmctl.2 index 4bfb2c5..5d5176a 100644 --- a/man2/shmctl.2 +++ b/man2/shmctl.2 @@ -24,7 +24,7 @@ .\" 2005-08-02, mtk: Added IPC_INFO, SHM_INFO, SHM_STAT descriptions. .\" 2018-03-20, dbueso: Added SHM_STAT_ANY description. .\" -.TH shmctl 2 2023-03-30 "Linux man-pages 6.05.01" +.TH shmctl 2 2024-03-03 "Linux man-pages 6.7" .SH NAME shmctl \- System V shared memory control .SH LIBRARY @@ -33,21 +33,21 @@ Standard C library .SH SYNOPSIS .nf .B #include <sys/shm.h> -.PP -.BI "int shmctl(int " shmid ", int " cmd ", struct shmid_ds *" buf ); +.P +.BI "int shmctl(int " shmid ", int " op ", struct shmid_ds *" buf ); .fi .SH DESCRIPTION .BR shmctl () performs the control operation specified by -.I cmd +.I op on the System\ V shared memory segment whose identifier is given in .IR shmid . -.PP +.P The .I buf argument is a pointer to a \fIshmid_ds\fP structure, defined in \fI<sys/shm.h>\fP as follows: -.PP +.P .in +4n .EX struct shmid_ds { @@ -64,7 +64,7 @@ struct shmid_ds { }; .EE .in -.PP +.P The fields of the .I shmid_ds structure are as follows: @@ -106,13 +106,13 @@ system call on this segment. .TP .I shm_nattch Number of processes that have this segment attached. -.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 { @@ -127,7 +127,7 @@ struct ipc_perm { }; .EE .in -.PP +.P The least significant 9 bits of the .I mode field of the @@ -143,7 +143,7 @@ l l. 0004 Read by others 0002 Write by others .TE -.PP +.P Bits 0100, 0010, and 0001 (the execute bits) are unused by the system. (It is not necessary to have execute permission on a segment in order to perform a @@ -151,9 +151,9 @@ in order to perform a call with the .B SHM_EXEC flag.) -.PP +.P Valid values for -.I cmd +.I op are: .TP .B IPC_STAT @@ -307,9 +307,11 @@ is not checked for read access for meaning that any user can employ this operation (just as any user may read .I /proc/sysvipc/shm to obtain the same information). -.PP +.P The caller can prevent or allow swapping of a shared -memory segment with the following \fIcmd\fP values: +memory segment with the following +.I op +values: .TP .BR SHM_LOCK " (Linux-specific)" Prevent swapping of the shared memory segment. @@ -325,7 +327,7 @@ will be set. .TP .BR SHM_UNLOCK " (Linux-specific)" Unlock the segment, allowing it to be swapped out. -.PP +.P Before Linux 2.6.10, only a privileged process could employ .B SHM_LOCK @@ -363,7 +365,7 @@ operation returns the identifier of the shared memory segment whose index was given in .IR shmid . Other operations return 0 on success. -.PP +.P On error, \-1 is returned, and .I errno is set to indicate the error. @@ -379,7 +381,7 @@ capability in the user namespace that governs its IPC namespace. .TP .B EFAULT The argument -.I cmd +.I op has value .B IPC_SET or @@ -392,8 +394,10 @@ isn't accessible. \fIshmid\fP points to a removed identifier. .TP .B EINVAL -\fIshmid\fP is not a valid identifier, or \fIcmd\fP -is not a valid command. +.I shmid +is not a valid identifier, or +.I op +is not a valid operation. Or: for a .B SHM_STAT or @@ -456,7 +460,7 @@ POSIX.1-2001, SVr4. .\" SVr4 documents additional error conditions EINVAL, .\" ENOENT, ENOSPC, ENOMEM, EEXIST. Neither SVr4 nor SVID documents .\" an EIDRM error condition. -.PP +.P Various fields in a \fIstruct shmid_ds\fP were typed as .I short under Linux 2.2 @@ -468,7 +472,7 @@ 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 .) +.IR op .) .SH NOTES The .BR IPC_INFO , |