Book Glossary

   

Glossary

. (dot)

A special file name that refers to the current directory.



.. (dot-dot)

A special file name that refers to the parent directory.



Absolute Path Name

A path name beginning with a slash (/).



Access Mode

A form of access permitted to a file.



Address Space

The range of memory locations to which a process can refer.



Archive

A file comprised of the contents of other files, such as the tar archive.



ASCII

An acronym for American Standard Code for Information Interchange.



Background Process

Any process that gives the shell prompt back to the user .



Backup

The process of making a copy of all or part of the file system in order to preserve it, in case a system crash occurs.



Block

The fundamental unit of information HP-UX uses for the access and storage location on a mass storage medium.



Block Special File

A special file associated with a mass storage device.



Boot, Boot-up

The process of loading, initializing, and running an operating system.



Boot Area

A portion of a mass storage medium on which the volume header and a "bootstrap" program used in booting the operating system reside.



Boot ROM

A program residing in ROM (Read-Only Memory) that executes each time the computer is powered up.



Bus Address

A number which makes up part of the address HP-UX uses to locate a particular device.



Character

An element used for the organization, control, or representation of text. Characters include graphic characters and control characters .



Character Set

A set of characters used to communicate in a native or computer language.



Character Special File

A special file associated with I/O devices that transfer data byte-by-byte.



Child Process

A new process created by a pre-existing process.



Command

A directive to perform a particular task.



Command Interpreter

A program which reads lines of text from standard input (typed at the keyboard or read from a file), and interprets them as requests to execute other programs. A command interpreter for HP-UX is called a shell.



Control Character

A character other than a graphic character that affects the recording, processing, transmission, or interpretation of text.



Controlling Terminal

A terminal that is associated with a session. Each session can have at most one controlling terminal associated with it, and a controlling terminal is associated with exactly one session.



Crash

The unexpected shutdown of a program or system. If the operating system crashes, this is a "system crash" and requires the system to be rebooted.



Current Directory
See [ Working Directory ]
Current Working Directory
See [ Working Directory ]
Daemon

A process which runs in the background, and which is usually immune to termination instructions from a terminal.



Default Search Path

The sequence of directory prefixes that HP-UX commands apply in searching for a file known by a relative path name (that is, a path name not beginning with a slash (/)).



Device

A computer peripheral or an object that appears to an application as such.



Device Address
See [ Bus Address ]
Device File
See [ Special File ]
Directory

A file that provides the mapping between the names of files and their contents, and that is manipulated by the operating system alone.



End-Of-File (EOF)

The data returned when attempting to read past the logical end of a file.



Environment

The set of defined shell variables .



EOF
See [ End-Of-File (EOF) ]
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.



FIFO Special File

A type of file. Data written to a FIFO is read on a first-in-first-out basis.



File

A stream of bytes that can be written to and/or read from.



File Access Mode

A characteristic of an open file description that determines whether the described file is open for reading, writing, or both.



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.



File Descriptor

A small, unique, per-process , nonnegative integer identifier that is used to refer to a file opened for reading and/or writing.



File Hierarchy

The collection of one or more file systems available on a system.



File Name

A string of up to 255 bytes used to refer to an ordinary file, special file, or directory.



File System

A collection of files and supporting data structures residing on a mass storage volume.



Filter

A command that reads data from the standard input, performs a transformation on the data, and writes it to the standard output.



Fork

An HP-UX system call, which, when invoked by an existing process, causes a new process to be created.



Graphic Character

A character other than a control character that has a visual representation when hand-written , printed, or displayed.



Group
See [ Group ID ]
Group ID

Associates zero or more users who must all be permitted to access the same set of files.



Home Directory

The directory name given by the value of the environment variable HOME. When you first log in, login(1) automatically sets HOME to your login directory.



Host Name

An ASCII string of at most 8 characters.



init

A system process that performs initialization.



Inode

An inode is a structure that describes a file and is identified in the system by a file serial number. Every file or directory has an inode associated with it.



Interrupt Signal

The signal sent by SIGINT.



I/O Redirection

A mechanism provided by the HP-UX shell for changing the source of data for standard input and/or the destination of data for standard output and standard error.



Job Control

Allows users to selectively stop (suspend) execution of processes and continue (resume) their execution at a later time.



Kernel

The HP-UX operating system. The kernel is the executable code responsible for managing the computer's resources, such as allocating memory, creating processes, and scheduling programs for execution.



LIF
See [ Logical Interchange Format ]
Link

A directory entry. It is an object that associates a file name with any type of file.



Link Count

The number of directory entries that refer to a particular file.



Logical Interchange Format
LIF

A standard format for mass storage implemented on many Hewlett-Packard computers to aid in media transportability.



Login

The process of gaining access to HP-UX.



Login Directory

The directory in which a user is placed immediately after logging in. This directory is defined for each user in the /etc/passwd file. The shell variable HOME is set automatically to the user's login directory by login .



Magic Number

The first word of an a.out-format or archive file. This word contains the system ID, which states what machine (hardware) the file will run on and the file type (executable, sharable executable, archive, etc.)



Major Number

A number used exclusively to create special files that enable I/O to or from specific devices. This number indicates which device driver to use for the device.



Meta Character

A character that has special meaning to the HP-UX shell, as well as to commands.



Minor Number

A number that is an attribute of special files, specified during their creation and used whenever they are accessed, to enable I/O to or from specific devices.



Newline Character

The character with an ASCII value of 10 (line feed) used to separate lines of characters.



Node Name

A string of up to 31 characters, not including control characters or spaces, that uniquely identifies a node on a Local Area Network (LAN).



Ordinary File

A type of HP-UX file containing ASCII text.



Orphan Process

A child process that is left behind when a parent process terminates for any reason. The init process inherits all orphan processes.



Owner

The owner of a file is usually the creator of that file. However, the ownership of a file can be changed by the superuser or the current owner.



Parent Directory

The directory one level above a directory in the file hierarchy.



Parent Process

Whenever a new process is created by a currently-existing process, the currently existing process is said to be the parent process of the newly created process.



Parent Process ID

A new process is created by a currently active process. The parent process ID of a process is the process ID of its creator for the lifetime of the creator.



Password

A string of ASCII characters used to verify the identity of a user.



Path name

A sequence of directory names separated by slashes and ending with any file name.



Pipe

An interprocess I/O channel used to pass data between two processes.



Process

An invocation of a program or the execution of an image. Although all commands and utilities are executed within processes, not all commands or utilities have a one-to-one correspondence with processes. Some commands (such as cd ) execute within a process, but do not create any new processes.



Process ID

A positive integer less than or equal to PID_MAX by which each active process in the system is uniquely identified during its lifetime.



Program

A sequence of instructions to the computer in the form of binary code.



Prompt

The characters displayed by the shell on the terminal indicating that the system is ready for a command.



Raw Disk

The name given to a disk for which there exists a character special file that allows direct transmission between the disk and the user's read or write buffer. A single read or write call results in exactly one I/O call.



Regular Expression

A string of zero or more characters that selects text.



Regular File

A type of file that is a randomly accessible sequence of bytes, with no further structure imposed by the system.



Relative Path Name

A path name that does not begin with a slash (/).



Root Directory

The highest level directory of the hierarchical file system.



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.



Secondary Prompt

One or more characters that the shell prints on the display, indicating that more input is needed.



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 ID ]


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.



Shell

A user interface to the HP-UX operating system. A shell often functions as both a command interpreter and an interpretive programming language.



Shell Program
See [ Shell Script ]
Shell Script

A sequence of shell commands and shell programming language constructs stored in a file and invoked as a user command (program). No compilation is needed prior to execution because the shell recognizes the commands and constructs that make up the shell programming language.



Signal

A software interrupt sent to a process, informing it of special situations or events.



Single-User State

A condition of the HP-UX operating system in which the system console provides the only communication mechanism between the system and its user.



Special File

A file associated with an I/O device. Often called a device file.



Standard Error

The destination of error and special messages from a program, intended to be used for diagnostic messages. The standard error output is often called stderr.



Standard Input

The source of input data for a program. The standard input file is often called stdin.



Standard Output

The destination of output data from a program. The standard output file is often called stdout .



stderr
See [ Standard Error ]
stdin
See [ Standard Input ]
stdout
See [ Standard Output ]
Sticky Bit

A single bit in the mode of every file in the file system. If set on a regular file, the contents of the file stay permanently in memory instead of being swapped back out to disk when the file has finished executing.



Subdirectory

A directory that is one or more levels lower in the file system hierarchy than a given directory.



Superblock

A block on each file system's mass storage medium which describes the file system.



Superuser

The HP-UX system administrator. This user has access to all files and can perform privileged operations. The superuser has a real user ID and an effective user ID of 0, and, by convention, the user name of root .



Symbolic Link

A type of file that indirectly refers to a path name.



System

The HP-UX operating system.



System Call

An HP-UX operating system kernel function available to the user through a high-level language.



System Console

A keyboard and display (or terminal) given a unique status by HP-UX and associated with the special file /dev/console . All boot ROM error messages, HP-UX system error messages, and certain system status messages are sent to the system console.



Terminal

A character special file that obeys the specifications of termio .



Text File

A file that contains characters organized into one or more lines.



tty

Originally, an abbreviation for teletypewriter; now, generally , a terminal.



User ID

Each system user is identified by an integer known as a user ID, which is in the range of zero to UID_MAX , inclusive.



Utility

An executable file, which might contain executable object code (that is, a program), or a list of commands to execute in a given order (that is, a shell script).



Volume Number

Part of an address used for devices.



Whitespace

One or more characters which, when displayed, cause a movement of the cursor or print head, but do not result in the display of any visible graphic.



Working Directory

Each process has associated with it the concept of a current working directory. For a shell, this appears as the directory in which you currently "reside."



Zombie Process

The name given to a process which terminates for any reason, but whose parent process has not yet waited for it to terminate (via wait(2) ). The process which terminated continues to occupy a slot in the process table until its parent process waits for it.




   
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HP Certified
HP Certified: HP-UX System Administration
ISBN: 0130183741
EAN: 2147483647
Year: 2000
Pages: 390
Authors: Rafeeq Rehman

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