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
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glossary(9) glossary(9)
(3) A character defined by stty(1) or ioctl(2) (see termio(7)) to act as end-of-file on your ter-
minal. 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 command (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 structure
on the contents of a file, although some programs do. Files can be accessed serially or ran-
domly (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.
Read, write, and execute/search permissions on a file are granted to a process if any of the
following conditions are met:
• The process’s effective user ID is superuser.
• The process’s effective user ID matches the user ID of the owner of the file and
the appropriate access bit of the owner portion (0700) of the file mode is set.
• The process’s effective user ID does not match the user ID of the owner of the
file, and either the process’s effective group ID matches the group ID of the file,
or the group ID of the file is in the process’s group access list, and the appropriate
access bit of the group portion (070) of the file mode is set.
HP-UX Release 11i: December 2000 − 6 − Section 9−−7
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