summaryrefslogtreecommitdiffstats
path: root/man7/shm_overview.7
diff options
context:
space:
mode:
Diffstat (limited to 'man7/shm_overview.7')
-rw-r--r--man7/shm_overview.7104
1 files changed, 0 insertions, 104 deletions
diff --git a/man7/shm_overview.7 b/man7/shm_overview.7
deleted file mode 100644
index a049e4c..0000000
--- a/man7/shm_overview.7
+++ /dev/null
@@ -1,104 +0,0 @@
-.\" Copyright (C) 2008, Linux Foundation, written by Michael Kerrisk
-.\" <mtk.manpages@gmail.com>
-.\"
-.\" SPDX-License-Identifier: Linux-man-pages-copyleft
-.\"
-.TH shm_overview 7 2023-10-31 "Linux man-pages 6.7"
-.SH NAME
-shm_overview \- overview of POSIX shared memory
-.SH DESCRIPTION
-The POSIX shared memory API allows processes to communicate information
-by sharing a region of memory.
-.P
-The interfaces employed in the API are:
-.TP 15
-.BR shm_open (3)
-Create and open a new object, or open an existing object.
-This is analogous to
-.BR open (2).
-The call returns a file descriptor for use by the other
-interfaces listed below.
-.TP
-.BR ftruncate (2)
-Set the size of the shared memory object.
-(A newly created shared memory object has a length of zero.)
-.TP
-.BR mmap (2)
-Map the shared memory object into the virtual address space
-of the calling process.
-.TP
-.BR munmap (2)
-Unmap the shared memory object from the virtual address space
-of the calling process.
-.TP
-.BR shm_unlink (3)
-Remove a shared memory object name.
-.TP
-.BR close (2)
-Close the file descriptor allocated by
-.BR shm_open (3)
-when it is no longer needed.
-.TP
-.BR fstat (2)
-Obtain a
-.I stat
-structure that describes the shared memory object.
-Among the information returned by this call are the object's
-size
-.RI ( st_size ),
-permissions
-.RI ( st_mode ),
-owner
-.RI ( st_uid ),
-and group
-.RI ( st_gid ).
-.TP
-.BR fchown (2)
-To change the ownership of a shared memory object.
-.TP
-.BR fchmod (2)
-To change the permissions of a shared memory object.
-.SS Versions
-POSIX shared memory is supported since Linux 2.4 and glibc 2.2.
-.SS Persistence
-POSIX shared memory objects have kernel persistence:
-a shared memory object will exist until the system is shut down,
-or until all processes have unmapped the object and it has been deleted with
-.BR shm_unlink (3)
-.SS Linking
-Programs using the POSIX shared memory API must be compiled with
-.I cc \-lrt
-to link against the real-time library,
-.IR librt .
-.SS Accessing shared memory objects via the filesystem
-On Linux, shared memory objects are created in a
-.RB ( tmpfs (5))
-virtual filesystem, normally mounted under
-.IR /dev/shm .
-Since Linux 2.6.19, Linux supports the use of access control lists (ACLs)
-to control the permissions of objects in the virtual filesystem.
-.SH NOTES
-Typically, processes must synchronize their access to a shared
-memory object, using, for example, POSIX semaphores.
-.P
-System V shared memory
-.RB ( shmget (2),
-.BR shmop (2),
-etc.) is an older shared memory API.
-POSIX shared memory provides a simpler, and better designed interface;
-on the other hand POSIX shared memory is somewhat less widely available
-(especially on older systems) than System V shared memory.
-.SH SEE ALSO
-.BR fchmod (2),
-.BR fchown (2),
-.BR fstat (2),
-.BR ftruncate (2),
-.BR memfd_create (2),
-.BR mmap (2),
-.BR mprotect (2),
-.BR munmap (2),
-.BR shmget (2),
-.BR shmop (2),
-.BR shm_open (3),
-.BR shm_unlink (3),
-.BR sem_overview (7)