commandliners

This command, when invoked without arguments, shows the list of aliases in your shell session:

$>alias
alias dir='ls -l'
alias l='ls -alF'
alias md='mkdir -p'

It also allows you to create your own aliases:

$>alias lc='ls --color'

If for some reason, you want to delete an alias, you can use the unalias command:

$>unalias lc

Aliases can help you saving a lot of time by avoiding repetitive and long commands and options.

If you want them to be permanent, you should add those definitions to your .bashrc file.