Codacy analyzer warning: In POSIX sh, [[ ]] is undefined

Question

When I run codacy-analysis-cli analyze command for the next line of script:

if [[ "$lexer_date" > "$lexer_ts_date" ]]; then
    generate_grammar
fi

I got the next warning: Found [Warning] `In POSIX sh, [[ ]] is undefined.` in scripts/grammar.sh:20 (shellcheck_SC2039)

How can I fix it?

Answer 1

Use [ instead. Note that for alphanumeric comparisons you need to quote the comparison operator; thus:

if [ "$lexer_date" ">" "$lexer_ts_date" ]; then
    generate_grammar
fi