HP-UX Reference (11i v1 05/09) - 7 Device (Special) Files, 9 General Information, Index (vol 10)

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glossary(9) glossary(9)
real user ID
A positive integer which is assigned to every user on the system. A real user ID is assigned to every valid
login name in the file /etc/passwd . The modifier "real" is used because a user can also have an
effective user ID (see effective user ID).
Every time a process creates a child process (via fork(2)), that process has a real user ID equal to the
parent process’s real user ID. This is useful for determining file access privileges within the process.
regular expression
A string of zero or more characters that selects text. All the characters contained in the string might be
literal, meaning that the regular expression matches itself only; or one or more of the characters might be a
metacharacter, meaning that a single regular expression could match several literal strings. Regular
expressions are most often encountered in text editors (such as ed(1), ex(1), or vi(1)), where searches are
performed for a specific piece of text, or in commands that were created to search for a particular string in
a file (most notably grep(1)). Regular expressions are also encountered in the shell, especially when refer-
ring to file names on command lines.
regular file
A type of file that is a randomly accessible sequence of bytes, with no further structure imposed by the sys-
tem. Its size can be extended. A regular file is also called an ordinary file.
relative path name
A path name that does not begin with a slash (
/). It indicates that a file’s location is given relative to
your current working directory, and that the search begins there (instead of at the root directory). For
example,
dir1/file2 searches for the directory dir1 in your current working directory; then dir1 is
searched for the file file2.
root directory
(1) The highest level directory of the hierarchical file system, from which all other files branch. In HP-
UX, the slash (/) character refers to the root directory. The root directory is the only directory in
the file system that is its own parent directory.
(2) Each process has associated with it a concept of a root directory for the purpose of resolving path
name searches for those paths beginning with slash (/). A process’s root directory need not be the
root directory of the root file system, and can be changed by the chroot(1M) command or chroot(2) sys-
tem call. Such a directory appears to the process involved to be its own parent directory.
root volume
The mass storage volume which contains the boot area (which contains the HP-UX kernel) and the root
directory of the HP-UX file system.
saved group ID
Every process has a saved group ID that retains the process’s effective group ID from the last successful
exec(2) or
setresgid() (see setresuid(2)), or from the last superuser call to setgid() (see setuid(2))
or setresuid(2).
setgid() permits a process to set its effective group ID to this remembered value. Con-
sequently, a process that executes a program with the set-group-ID bit set and with a group ID of 5 (for
example) can set its effective group ID to 5 at any time until the program terminates. See exec(2),
setuid(2), saved user ID, effective group ID, and set-group-ID bit. The saved group ID is also known
as the saved set-group-ID.
saved process group ID
Every process has a saved process group ID that retains the process’s group ID from the last successful
exec(2). See setpgrp(2), termio(7), and process group ID.
saved user ID
Every process has a saved user ID that retains the process’s effective user ID from the last successful
exec(2) or setresuid(2), or from the last superuser call to setuid(2). setuid(2) permits a process to set its
effective user ID to this remembered value. Consequently, a process which executes a program with the
set-user-ID bit set and with an owner ID of 5 (for example) can set its effective user ID to 5 at any time
until the program terminates. See exec(2), setuid(2), saved group ID, effective user ID, and set-user-
ID bit. The saved user ID is also known as the saved set-user-ID.
HP-UX 11i Version 1: September 2005 − 18 − Hewlett-Packard Company Section 9−−19