If you set environment variables like your $EDITOR in your .bashrc file that refer to commands that you expect to be available on the system, it’s prudent to check that an appropriate command actually exists before making the setting.

A common way of approaching this is using which, in a syntax similar to the below, which sets the $EDITOR to the first executable instance of vi found in $PATH, or blank if not found:

EDITOR=`which vi`

Because the behaviour of which can be unexpected, it’s better practice to use one of Bash’s builtins to do this, either command, type, or hash. I prefer using hash, which searches $PATH for a command of the given name, and loads it into Bash’s command hash table if found. An implementation like the below works well:

hash vi &>/dev/null
if [ $? -eq 0 ]; then
    export EDITOR=vi
fi

This ignores any output from the hash call by redirecting it to the null device, and checks its return value in the special $? variable, only defining the value for $EDITOR if a matching command is found.

You can compact this syntax into one line:

hash vi &>/dev/null && export EDITOR=vi

Thanks to commenter Yu-Jie Lin for pointing out the above abbreviation.