HP-UX Reference (11i v1 00/12) - 5 Miscellaneous Topics, 7 Device (Special) Files, 9 General Information, Index (vol 9)
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STANDARD Printed by: Nora Chuang [nchuang] STANDARD
/build/1111/BRICK/man9/!!!intro.9
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glossary(9) glossary(9)
groups that remain as members of the session.
set-group-ID bit
A single bit in the mode of every file in the file system. If a file is executed whose set-
group-ID bit is set, the effective group ID of the process which executed the file is set
equal to the real group ID of the owner of the file. See also group.
set-user-ID bit
A single bit in the mode of every file in the file system. If a file is executed whose set-
user-ID bit is set, the effective user ID of the process that executed the file is set equal
to the real user ID of the owner of the file.
shared library
An executable file that can be shared between several different programs. Code from a
shared library is not linked into the program by ld(1), but is instead mapped into the pro-
cess’ address space at run time by the dynamic loader. Shared libraries must contain
position-independent code, and are created by ld(1). They typically have the file name
suffix .sl.
shared memory identifier (shmid)
A unique positive integer created by a shmget(2) system call. Each shmid has a segment
of memory (referred to as a shared memory segment) and a data structure associated with
it. The data structure is referred to as
shmid_ds and contains the following members:
struct
ipc_perm shm_perm; /* operation permission struct */
int shm_segsz; /* size of segment */
ushort shm_cpid; /* creator pid */
ushort shm_lpid; /* pid of last operation */
uint shm_nattch; /* number of current attaches */
time_t shm_atime; /* last attach time */
time_t shm_dtime; /* last detach time */
time_t shm_ctime; /* last change time */
/* Times measured in secs since */
/* 00:00:00 GMT, Jan. 1, 1970 */
Shared memory identifiers can be created using ftok(3C).
shm_perm is a ipc_perm structure that specifies the permission for a shmop(2) or
shmctl(2) operation (see below). This structure includes the following members:
ushort cuid; /* creator user id */
ushort cgid; /* creator group id */
ushort uid; /* user id */
ushort gid; /* group id */
ushort mode; /* r/w permission */
shm_segsz
specifies the size of the shared memory segment. shm_cpid is the process
id of the process that created the shared memory identifier. shm_lpid is the process id of
the last process that performed a shmop(2) operation. shm_nattch is the number of
processes that currently have this segment attached. shm_atime is the time of the last
shmat operation, shm_dtime is the time of the last shmdt operation, and
shm_ctime is the time of the last shmctl(2) operation that changed one of the members of
the above structure.
shared memory operation permissions
In the shmop(2) and shmctl(2) system call descriptions, the permission required for an
operation is indicated for each operation. Whether a particular process has the permission
to perform a shmop(2) or shmctl(2) operation on an object is determined by the object’s per-
mission mode bits as follows:
00400 Read by user
00200 Write by user
00060 Read, Write by group
00006 Read, Write by others
Read and Write permissions for a shmop(2) or shmctl(2) operation on a shared memory
identifier (shmid) are granted to a process if one or more of the following are true:
Section 9−−20 − 19 − HP-UX Release 11i: December 2000
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