<sys/shm.h>(P) POSIX Programmer's Manual <sys/shm.h>(P)
sys/shm.h - XSI shared memory facility
The <sys/shm.h> header shall define the following symbolic constants:
Attach read-only (else read-write).
Round attach address to SHMLBA.
The <sys/shm.h> header shall define the following symbolic value:
SHMLBA Segment low boundary address multiple.
The following data types shall be defined through typedef:
Unsigned integer used for the number of current attaches that must be able to store
values at least as large as a type unsigned short.
The shmid_ds structure shall contain the following members:
struct ipc_perm shm_perm Operation permission structure.
size_t shm_segsz Size of segment in bytes.
pid_t shm_lpid Process ID of last shared memory operation.
pid_t shm_cpid Process ID of creator.
shmatt_t shm_nattch Number of current attaches.
time_t shm_atime Time of last shmat
time_t shm_dtime Time of last shmdt
time_t shm_ctime Time of last change by shmctl
The pid_t, time_t, key_t, and size_t types shall be defined as described in <sys/types.h>
The following shall be declared as functions and may also be defined as macros. Function
prototypes shall be provided.
void *shmat(int, const void *, int);
int shmctl(int, int, struct shmid_ds *);
int shmdt(const void *);
int shmget(key_t, size_t, int);
In addition, all of the symbols from <sys/ipc.h> shall be defined when this header is
The following sections are informative.
<sys/ipc.h> , <sys/types.h> , the System Interfaces volume of IEEE Std 1003.1-2001,
shmat(), shmctl(), shmdt(), shmget()
Portions of this text are reprinted and reproduced in electronic form from IEEE Std
1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System
Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by
the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and The Open Group
Standard, the original IEEE and The Open Group Standard is the referee document. The orig-
inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .
IEEE/The Open Group 2003 <sys/shm.h>(P)