CompTIA Linux+ XK0-006 (V8) Practice Question

The correct answer uses the extended test construct [[...]] with the > operator. In Bash, when the > operator is used within [[...]], it performs a lexicographical (alphabetical) comparison based on the current locale's collation order. It correctly determines if the string on the left ($USERNAME) is "greater than" (comes after) the string on the right ("m").

The option if [ "$USERNAME" > "m" ] is incorrect because inside the legacy [ test construct, the > character is treated by the shell as an output redirection operator, not a comparison operator. This command would attempt to write the output of [ "$USERNAME" ] into a file named m.

The option if [[ "$USERNAME" -gt "m" ]] is incorrect because -gt is a numerical comparison operator (greater than) and should be used for comparing integers, not for lexicographical string comparison.

The option if ( "$USERNAME" > "m" ) is incorrect as parentheses (...) are used to execute commands in a subshell, not to perform conditional tests of this type. The correct construct for conditional tests is if [[...]] or if [...].