Peng Yu writes:
Could you show me how you do the profiling for this specific case? Based on what proof that you can conclude that it is not the `[[` performance problem?
Like I said, `perf` is perfectly adequate. bash -c 'x=$(printf "%.sx" {1..10000000}); perf record -g -p $$ & sleep 2; time [[ $x ]]' You might as well just use `:`.