alias Pop Quiz

Shells and Shell Scripting

• The shell is an interface between the user and the kernel of the operating system, and it interprets commands entered by the user.

Customize and Use the Shell Environment

• Set environment variables (e.g. PATH) at login or when spawning a new shell.
• Write Bash functions for frequently used sequences of commands.
• Maintain skeleton directories for new user accounts.
• Set command search path with the proper directory.

Startup Scripts

• Startup scripts customize the session's environment.
• There are both system-wide and user-specific scripts.
• Scripts can include personal preferences or settings, such as variables, aliases, and functions.

Shell Types

• Shells can be interactive or non-interactive, and login or non-login.

Shell Environment

• The shell environment consists of variables, aliases, and functions.
• These elements can be influenced by each other.

Aliases

• An alias is a substitute name for another command(s).
• Aliases can run like regular commands, but execute another command according to the alias definition.
• The syntax for declaring aliases is alias followed by the alias assignment.

Functions

• Functions are used to put together repetitive or recurrent commands under a single command.
• Functions offer the possibility of encapsulation.

Bash Startup Files

• Files such as /etc/bash.bashrc, /etc/profile, ~/.bash_profile, ~/.bash_login, ~/.bashrc, and ~/.bash_logout are used to customize the shell environment.