Check to see if a command exists at #shell

If you want to check to see if a command exists on a user's machine you can use command -v. command without flags will run the command passed as an argument.

> command echo "A"
"A"

command -v with the -v flag will return the path of the command, and most importantly, a non-zero status code if that command does not exist.

> command -v brew
/usr/local/bin/brew

Or on Linux

> command -v brew
# returns nothing and also returns a status code of 1

Importantly, you can check for a command before using it.

command -v brew && brew install something

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