Unix Operating System and Shell Programming

Flashcards covering key vocabulary and concepts related to the Unix Operating System and Shell Programming.

Unix

A time-sharing operating system designed for multitasking and simplicity.

Kernel

The core component of the Unix operating system responsible for managing system resources.

Shell

A command interpreter in Unix that executes user commands and scripts.

Bourne shell

A command line shell in Unix, created by Steve Bourne, prompt symbol is '$'.

C shell

A shell variant for BSD Unix systems created by Bill Joy, uses '%' as its prompt.

Korn shell

A shell combining C and Bourne shell features, designed by Dave Korn.

Hierarchical structure

An organizational method for files in Unix, allowing for a tree-like directory arrangement.

File links

Permits multiple names to reference the same data clusters in Unix.

Access types

Defines the permissions for files in Unix: read (r), write (w), execute (x), or no access (-).

ls

A command that lists the contents of a directory.

pwd

Present working directory; displays the current directory path.

mkdir

Creates a new directory with the specified name.

rm

Removes a specified file or directory.

cp

Copies files from a source to a destination.

mv

Moves or renames a file.

cat

Concatenates files and displays their content.

more

Displays contents of a file one screen at a time.

cmp

Compares two files to check if they are equal.

diff

Lists the differences between two files.

chmod

Changes the access permissions of a file.

Shell script

A program written for the shell that automates tasks in Unix.

Environment variables

Variables that influence the behavior of processes in Unix.

Input/output redirection

Directs the input or output to/from files or devices rather than the default.

Command substitution

A feature that allows the output of a command to replace the command itself.

Decision statement

A conditional expression used to execute commands based on boolean conditions.

Looping constructs

Structures for repeating a set of commands multiple times based on conditions.

Wildcards

Special characters that represent one or more characters in Unix commands.

Filters

Programs that read input, process it, and produce output, like grep and sed.

Function

A reusable block of code in a shell script that performs a specific task.

Variable assignment

Assigning a value to a variable using the syntax: varname=value.

getopts

A built-in command for processing command-line options in shell scripts.

stdin

Standard Input; the default source for reading data, typically the keyboard.

stdout

Standard Output; the default destination for printing output, usually the terminal.

stderr

Standard Error; the default destination for displaying error messages.

Piping

A method for passing the output of one command directly as input to another command.

Redirection symbols

Special characters used to handle the input and output of commands (e.g., >, <, |).

Concurrent access

Multiple processes accessing a file at the same time in Unix.

Script execution

Running a shell script after making it executable.

Comments

Annotations in code denoted by # which are ignored by the shell during execution.

Access control

The management of permissions to read, write, or execute files in Unix.

Dynamic memory

Memory allocation that allows files in Unix to grow as needed.

Function parameters

Arguments passed to functions in shell scripts, accessed using $1, $2, etc.

Conditional execution

Executing commands based on the result of a test or condition.

Command line argument

An input value passed to a script or program via the command line.

File system

The method and data structures that the operating system uses to manage files.

User interface

The means by which users interact with the Unix shell and its commands.

Script editor

A text editor used to write and modify shell scripts.

Error handling

The process of managing errors that occur during command execution in scripts.

Shell environment

The context or state in which shell commands are executed.

Batch processing

Executing a series of commands or scripts without user interaction.

Variable scope

The context within which a variable is accessible and can be used in a shell script.

System libraries

Predefined functions in Unix that programs can use for standard operations.