Linux urldecode filename

Question

Is there any tool to urldecode a file's name and replace it?

Example:

$ ls
hello%20world.txt
$ urldecode *.txt
$ ls
hello world.txt

Answer 1

A new blog post covers this with echo(1) and printf(1).

urldecode() {
  arg="$1"
  i="0"
  while [ "$i" -lt ${#arg} ]; do
    c0=${arg:$i:1}
    if [ "x$c0" = "x%" ]; then
      c1=${arg:$((i+1)):1}
      c2=${arg:$((i+2)):1}
      printf "\x$c1$c2"
      i=$((i+3))
    else
      echo -n "$c0"
      i=$((i+1))
    fi
  done
}

Answer 2

sed and echo can help out like so:

$ echo -n -e "$(echo hello%20world+ok | sed 's/+/ /g;s/%\(..\)/\\x\1/g;')"
hello world ok

Edit: Per SamB's comment:

$ ls *.txt
hello%20%20world++ok?.txt
$ for file in *.txt; do 
>   mv "${file}" "$(echo -n -e "$(echo "${file}" | sed 's/+/ /g;s/%\(..\)/\\x\1/g;')")"; 
> done
$ ls *.txt
hello  world  ok?.txt

Answer 3

I think this Perl snippet can be used as a base for what you are looking for.