It's not advanced, it's not long enough, and it's not correct either. > This will set the value of TMP to `/tmp/myproject` only if it has not been set. This s

It's not advanced, it's not long enough, and it's not correct either. > This will set the value of TMP to `/tmp/myproject` only if it has not been set. This should read "if", not "only if". And it should read: "This will set the value of TMP to `/tmp/myproject` if it has not been set or if it is null." The form that means 'if it has not been set' has no colon; it is TMP=${TMP-/tmp/myproject} See https://www.gnu.org/software/bash/manual/bash.html#Shell-Parameter-Expansion https://www.gnu.org/software/bash/manual/bash.html#Shell-Par...