How return from .bashrc if not run interactively?

Question

I have two statements to return from ~/.bashrc if the shell is not interactive, probably from two Ubuntu versions, but I can't reconstruct which one is newer (and I assume thus better) and I'm interested in the effect of the different approaches:

# If not running interactively, don't do anything
[ -z "$PS1" ] && return

vs.

# If not running interactively, don't do anything
case $- in
    *i*) ;;
      *) return;;
esac

Answer 1

According to the Bash Hackers Wiki, the most reliable method is to check for the existance of the i letter in the variable $- (your second method).

There are cleaner ways to implement this action, like the following:

[[ $- == *i* ]] || return

For more information, check this answer on the Unix&Linux StackExchange community.