One-liners

Compare command output with expectations

diff -u expected.txt <(some command)

URL-decode CLI

echo -n "%21%20" | python3 -c "import sys; from urllib.parse import unquote; print(unquote(sys.stdin.read()));"

Rename the files to lowercase

Try this:

for file in * ; do lower=$(echo $file | tr A-Z a-z) && [[ $lower != $file ]] && echo mv $file $lower ;done

To do the job remove the echo.