HP-UX Reference (11i v2 03/08) - 5 Miscellaneous Topics, 7 Device (Special) Files, 9 General Information, Index (vol 9)

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glossary(9) glossary(9)
process appear to be the file’s owner, enabling the process to access files which must be
accessed in order for the program to execute successfully. (Many HP-UX commands
which are owned by root, such as
mkdir and mail, have their set-user-ID bit set so
other users can execute these commands.) If the file’s set-user-ID bit is not set, the
process’s effective user ID is inherited from that process’s parent. See real user ID and
set-user-ID bit.
end-of-file (EOF)
(1) The data returned when attempting to read past the logical end of a file via stdio(3S)
routines. In this case, end-of-file is not properly a character.
(2) The ASCII character Ctrl-
D.
(3) A character defined by stty(1) or ioctl (2) (see termio (7)) to act as end-of-file on your
terminal. Usually this is Ctrl-
D.
(4) The return value from read(2) that indicates end of data.
environment The set of defined shell variables (such as
EXINIT, HOME, PATH, SHELL, TERM, and oth-
ers) that define the conditions under which user commands run. These conditions can
include user terminal characteristics, home directory, and default search path. Each
shell variable setting in the current process is passed on to all child processes that are
created, provided that each shell variable setting has been exported via the
export com-
mand (see sh(1)). Unexported shell variable settings are meaningful only to the current
process, and any child processes created get the default settings of certain shell variables
by executing /etc/profile, $HOME/.profile
,or$HOME/.login.
EOF See end-of-file.
Epoch The time period beginning at 0 hours, 0 minutes, 0 seconds, Coordinated Universal
Time (UTC) on January 1, 1970. Increments quantify the amount of time elapsed from
the Epoch to the referenced time.
Leap seconds, which occur at irregular intervals, are not reflected in the count of seconds
between the Epoch and the referenced time. (Fourteen leap seconds occurred in the
years 1970 through 1988.)
FIFO special file
A type of file. Data written to a FIFO is read on a first-in-first-out basis. Other charac-
teristics are described in open(2), read(2), write(2) and lseek(2).
file A stream of bytes that can be written to and/or read from. A file has certain attributes,
including permissions and type. File types include regular file, character special file,
block special file, FIFO special file, network special file, directory, and symbolic
link. Every file must have a file name that enables the user (and many of the HP-UX
commands) to refer to the contents of the file. The system imposes no particular struc-
ture on the contents of a file, although some programs do. Files can be accessed serially
or randomly (indexed by byte offset). The interpretation of file contents and structure is
up to the programs that access the file.
file access mode
A characteristic of an open file description that determines whether the described file
is open for reading, writing, or both. (See open(2).)
file access permissions
Every file in the file hierarchy has a set of access permissions. These permissions are
used in determining whether a process can perform a requested operation on the file
(such as opening a file for writing). Access permissions are established when a file is
created via the open(2) or creat(2) system calls, and can be changed subsequently
through the chmod(2) call. These permissions are read by stat (2) or fstat (2).
File access controls whether a file can be read, written, or executed. Directory files use
the execute permission to control whether or not the directory can be searched.
File access permissions are interpreted by the system as they apply to three different
classes of users: the owner of the file, the users in the file’s group, and anyone else
(‘‘other’’). Every file has an independent set of access permissions for each of these
classes. When an access check is made, the system decides if permission should be
granted by checking the access information applicable to the caller.
HP-UX 11i Version 2: August 2003 − 6 − Hewlett-Packard Company Section 9−−7