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Shell scripts are text files that automate a series of UNIX environment-based commands that otherwise must be performed one at a time. Shell scripts are often used to automate command sequences that repeat, such as services that start or stop on system start up or shut down. Any command that can be performed from the

Options are switches that control the behavior of the Korn shell. Options are boolean, meaning that they can be either on or off. To switch an option on, type: $ set -o option_name To switch an option off, type: $ set +o option_name To show current option settings, type: $ set -o Note: The set

Functions are a powerful feature of shell programming used to construct customized commands. A function is a group of UNIX commands organized as separate routines. Using a function involves two steps: Define the function. Invoke the function. Defining a Function A function is defined using the general format: function_name { command; . . . command;

An alias is a shorthand notation in the Korn shell to enable you to customize and abbreviate UNIX commands. An alias is defined by using the alias command. 3>Command Format The alias command syntax is as follows: alias name=command_string For example: $ alias dir=’ls -lF’ The shell maintains a list of aliases that it searches

The Korn shell enables you to run jobs in the background, which frees your terminal to perform other commands. You can also run jobs in the foreground. You can use Korn shell commands to list current jobs as well as to stop a job. A job is a process that the shell can manage. Shells