Tip: Shell aliases with sudo
Here is a quick tip for you.
Have you ever tried using your shell aliases in combination with the
sudo command? Yeah, does not work. The reason being that shell aliases are a simple ‘text substitution’ mechanism and by default, only the first word in a command is checked to see if it has an alias. However, if the last character of an alias is a space, the following word is also checked for alias expansion.
In order to use your aliases when using
sudo, you need to create an alias for the
sudo command itself. Aliasing it to
<space>) will force the following word to be evaluated as an alias as well.
alias sudo="sudo "
$ alias show-logs="cat /var/log/nginx/access.log" $ show-logs cat: /var/log/nginx/access.log: Permission denied $ sudo show-logs sudo: show-logs: command not found $ alias sudo="sudo " $ sudo show-logs 184.108.40.206 - - [24/Jan/2018:22:48:12+0000] "GET / HTTP/1.1" 301 194 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/57.0.2987.133 Safari/537.36" . . .
More detailed description of how alias expansion works can be found in the Bash Reference Manual.
Neat, right? That’s it. Bye bye 👋
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