It is very usefull to know how to temporary unalias an alias. There are some cases when you really need to do that, in your Linux / Unix box.
I will explain this with a practical example:
I have aliased shutdown to do ‘shutdown -h now’:
$ alias shutdown='shutdown -h now'
Having this alias, it is enough to type shutdown in the terminal and my system will turn itself off instantly.
But if I need to schedule a shutdown at 20:00, for example: shutdown -h 20:00, the shutdown alias will mess up my scheduled shutdown. So I will have to unalias the shutdown alias first.
unalias shutdown will unalias my shutdown alias until I my first relogin:
$ unalias shutdown
And now I can use:
$ sudo shutdown -h 20:00 .
The easiest solution to this problem is to escape the shutdown command with \ . The command \shutdown -h 20:00 will turn off my system at 20:00, ignoring my shutdown alias.
$ sudo \shutdown -h 20:00
The \ character before a command will tell the shell to use the system command, not an alias or function.