CompTIA Linux+ XK0-006 (V8) Practice Question

Inside Bash's [[...]] compound command, the operators for lexical string comparison are < (less than) and > (greater than). There are no built-in <= or >= operators for strings, so an expression such as [[ $alpha <= $beta ]] triggers a syntax error. Likewise, -le and its relatives are numeric operators; using them on strings either fails or produces misleading results. To emulate "less than or equal" for strings, you must combine the equality and less-than tests in a single expression using a logical OR. The correct option therefore uses [[ "$alpha" == "$beta" || "$alpha" < "$beta" ]], which returns true when the two strings are identical or when $alpha sorts before $beta. All other options either invoke an unsupported operator (<=), attempt a numeric comparison of non-numeric data (-le), or rely on [...] where < is parsed as a redirection symbol rather than a comparison operator.