1SHMDT(3P)                  POSIX Programmer's Manual                 SHMDT(3P)
2
3
4

PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
10
11

NAME

13       shmdt — XSI shared memory detach operation
14

SYNOPSIS

16       #include <sys/shm.h>
17
18       int shmdt(const void *shmaddr);
19

DESCRIPTION

21       The shmdt() function operates on XSI shared memory (see the Base  Defi‐
22       nitions  volume  of POSIX.1‐2008, Section 3.342, Shared Memory Object).
23       It is unspecified whether this function interoperates with the realtime
24       interprocess communication facilities defined in Section 2.8, Realtime.
25
26       The  shmdt() function detaches the shared memory segment located at the
27       address specified by shmaddr from the  address  space  of  the  calling
28       process.
29

RETURN VALUE

31       Upon  successful  completion,  shmdt()  shall  decrement  the  value of
32       shm_nattch in the data structure associated with the shared  memory  ID
33       of the attached shared memory segment and return 0. Also, the shm_dtime
34       timestamp shall be set to the current time,  as  described  in  Section
35       2.7.1, IPC General Description.
36
37       Otherwise,  the  shared  memory  segment shall not be detached, shmdt()
38       shall return −1, and errno shall be set to indicate the error.
39

ERRORS

41       The shmdt() function shall fail if:
42
43       EINVAL The value of shmaddr is not the data segment start address of  a
44              shared memory segment.
45
46       The following sections are informative.
47

EXAMPLES

49       None.
50

APPLICATION USAGE

52       The  POSIX Realtime Extension defines alternative interfaces for inter‐
53       process communication. Application  developers  who  need  to  use  IPC
54       should design their applications so that modules using the IPC routines
55       described in Section 2.7, XSI Interprocess Communication can be  easily
56       modified to use the alternative interfaces.
57

RATIONALE

59       None.
60

FUTURE DIRECTIONS

62       None.
63

SEE ALSO

65       Section  2.7,  XSI  Interprocess  Communication, Section 2.8, Realtime,
66       exec,  exit(),  fork(),  shmat(),   shmctl(),   shmget(),   shm_open(),
67       shm_unlink()
68
69       The Base Definitions volume of POSIX.1‐2008, Section 3.342, Shared Mem‐
70       ory Object, <sys_shm.h>
71

73       Portions of this text are reprinted and reproduced in  electronic  form
74       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
75       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
76       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
77       cal and Electronics Engineers,  Inc  and  The  Open  Group.   (This  is
78       POSIX.1-2008  with  the  2013  Technical Corrigendum 1 applied.) In the
79       event of any discrepancy between this version and the original IEEE and
80       The  Open Group Standard, the original IEEE and The Open Group Standard
81       is the referee document. The original Standard can be  obtained  online
82       at http://www.unix.org/online.html .
83
84       Any  typographical  or  formatting  errors that appear in this page are
85       most likely to have been introduced during the conversion of the source
86       files  to  man page format. To report such errors, see https://www.ker‐
87       nel.org/doc/man-pages/reporting_bugs.html .
88
89
90
91IEEE/The Open Group                  2013                            SHMDT(3P)
Impressum