Glossary

Alias

A name used as an abbreviation for one or more commands. An alias allows you to replace any command string with a short sequence of characters.

Applesoft

An implementation of BASIC for the Apple II.

APW

Apple Programmer's Workshop. Similar to ORCA.

BASIC

Beginners All-purpose Symbolic Instruction Code. A simple computer language.

Built-in Command

A command processed by gsh. These commands are not external to the shell, but are included within the gsh program.

Command

An action for gsh to perform. Commands can be either simple or compound. A simple command is an alias assignment, variable assignment, I/O redirection, or built-in command. A compound command is a pipeline.

Directory

A special type of file that contains a list of other files; usually used to categorize files related in some way.

Environment

The state of a process, which includes information such as its open files, current directory (working directory), and local and global variables. Three environments exist under gsh:

Child Environment

The environment of the child process.

Current Environment

The environment of the current process.

Parent Environment

The environment of the parent process.

Environment file

A file that is interpreted by an application to allow the user to customize its operation. For gsh, this file is gshrc.

Export

A way to pass a variable from a parent process to child process.

File

An object used to store data and/or programs. On the IIgs, files are tagged with types such as EXE, SRC, TXT, and so forth.

Filter

A command that reads from its standard input and writes to its standard output. For example, a filter program could be written to convert all characters to upper case. Filters are used mainly in pipelines.

Flag

A character used to represent an option to a command. Flags are either short or long options whose character representations are "-" and "+".

Glob

Slang for Pathname Expansion.

GNO/ME

GNO Multitasking Environment. The complete package including the GNO kernel and the GNO Shell.

GNO Kernel

Heart of GNO/ME. Executes processes when asked by the GNO Shell.

GNO Shell

Provides an interface between the user and the GNO kernel.

gsh

GNO Implementation of a UNIX-like shell.

GS/OS

16 bit Operating System for the Apple IIgs.

History

A variable number of command-lines saved by gsh for future reference. The number of command-lines saved is dependent on the HISTORY environment variable.

History file

A file containing command-lines entered while in a gsh session. The number of command-lines saved is dependent on the SAVEHIST environment variable.

Interrupt

A signal generated by a sequence of keyboard characters or by a command that terminates the current executing process, unless the process has set up a trap to handle the interrupt signal.

I/O Redirection

The process of changing the standard input, standard output, and standard error associated with a process so that it is redirected to a file instead of the console.

Job

A set of related processes. A job can be either:

Background Job

A process that executes with the current process. Background jobs are not associated with the terminal.

Foreground Job

A process that is currently executing and which is associated with the terminal.

Multiprocessing

Indicates a machine with more than one CPU.

Multitasking

The ability to run more than one program at a time, or the illusion of more than one program running at a time; usually the latter.

ORCA

Shell programing environment for the Apple //gs. Also a type of whale.

Path Search

The means of searching a pathname list for a command or script.

Pathname

A string used to identify a file.

Pathname Completion

The means of generating all pathnames matching a given pattern.

Pathname Expansion

The means of replacing a pattern with a list of pathnames matching that pattern.

Pattern

A string of characters used to match literal characters and/or multiple characters.

Permission

Each file has certain permissions associated with it: destroy, rename, backup, invisible, write, and read.

Pipe

A conduit through which a stream of characters can pass from one process to another. This is accomplished by linking the standard output of one process to the standard input of a second process.

Pipeline

Two or more processes connected together by pipes.

Process

A single thread of execution that consists of a program and an execution environment. If a process creates another process, the creator is known as the parent process; the created process is known as the child process.

Process ID

Each active process is uniquely identified by a positive integer called the process id.

ProDOS

8-bit Disk Operating System for Apple II computers.

Prompt

A message displayed by gsh when it is ready to receive a command.

Quoting

A means of including special characters as arguments to a command or as the command name. Certain characters have certain meanings to gsh and quoting them makes gsh ignore them.

Reserved Word

A word that is treated specially by gsh. This word is part of the gsh grammar.

Script

A sequence of commands contained in a file.

Signal

An asynchronous message that consists of a number or name that can be sent from one process to another.

Standard Error

The file associated with error messages for a process. This file is usually the terminal.

Standard Input

The file associated with a processes input. This file is usually the terminal.

Standard Output

The file associated with a processes output. This file is usually the terminal.

Tilde Expansion

Words beginning with "~" are treated specially by gsh. The "~" is expanded to the value of the HOME environment variable.

UNIX

Popular operating system which has growing use in education and business. One of the first operating systems to support multitasking.

Variable

A named location in gsh that contains text. The text of a variable can be expanded in a command by preceding the variable name with a dollar sign ($).

Wildcard

See Pattern and Pathname Expansion.

Working directory

The current directory.