Bash nonzero test case (-n), [ and [[ are doing different things

Question

Usually i only use [[ for all kinds of test cases, because it\'s the most advanced way and it\'s more safe to use (Regex, ...). I know that [[ executes different code than [

Answer 1

Quoting. You have to quote variables that you use in [:

$ VAR=    
$ [ -n $VAR ]
$ echo $?
0
$ [ -n "$VAR" ]
$ echo $?
1