Overriding Commands in bash

In Bash, you can override commands or create command aliases using the alias command or by creating functions with the same name as an existing command. This allows you to redefine the behavior of a command or create shortcuts for frequently used commands.

1. Using alias: The alias command allows you to create a short name or alias for a command. You can define an alias by assigning a command to a variable using the following syntax:

alias alias_name='command'

For example, let’s say you want to create an alias called ll for the ls -l command:

alias ll='ls -l'

Now, when you run ll, it will execute ls -l instead.

Aliases are temporary and exist only within the current shell session. If you want to make aliases persistent, you can add them to your shell configuration file (e.g., .bashrc, .bash_profile).

2. Creating functions: You can also create functions with the same name as an existing command to override its behavior. Bash will prioritize the function over the command with the same name.

For example, let’s say you want to override the ls command to always display files in long format (ls -l):

ls() {
    command ls -l "$@"
}

In this example, the ls function is defined to call the original ls command with the -l option and any additional arguments passed to it.

By defining the function, whenever you use the ls command, it will execute the function instead of the original command.

It’s important to exercise caution when overriding commands, as it can lead to unexpected behaviour and potential issues. Make sure to choose meaningful names for aliases and functions to avoid confusion and conflicts with existing commands or scripts.