If you are using Python 3, you can use urllib.parse.unquote:

url = """example.com?title=%D0%BF%D1%80%D0%B0%D0%B2%D0%BE%D0%B2%D0%B0%D1%8F+%D0%B7%D0%B0%D1%89%D0%B8%D1%82%D0%B0"""

import urllib.parse
urllib.parse.unquote(url)

gives:

'example.com?title=правовая+защита'

urllib.unquote will do the trick

sed

Try the following command line:

$ sed 's@+@ @g;s@%@\\x@g' file | xargs -0 printf "%b"

or the following alternative using echo -e:

$ sed -e's/%\([0-9A-F][0-9A-F]\)/\\\\\x\1/g' file | xargs echo -e

^{Note: The above syntax may not convert + to spaces, and can eat all the newlines.}

You may define it as alias and add it to your shell rc files:

$ alias urldecode='sed "s@+@ @g;s@%@\\\\x@g" | xargs -0 printf "%b"'

Then every time when you need it, simply go with:

$ echo "http%3A%2F%2Fwww" | urldecode
http://www

Bash

When scripting, you can use the following syntax:

input="http%3A%2F%2Fwww"
decoded=$(printf '%b' "${input//%/\\x}")

However above syntax won't handle pluses (+) correctly, so you've to replace them with spaces via sed or as suggested by @isaac, use the following syntax:

decoded=$(input=${input//+/ }; printf "${input//%/\\x}")

You can also use the following urlencode() and urldecode() functions:

urlencode() {
    # urlencode <string>
    local length="${#1}"
    for (( i = 0; i < length; i++ )); do
        local c="${1:i:1}"
        case $c in
            [a-zA-Z0-9.~_-]) printf "$c" ;;
            *) printf '%%%02X' "'$c" ;;
        esac
    done
}
 
urldecode() {
    # urldecode <string>
 
    local url_encoded="${1//+/ }"
    printf '%b' "${url_encoded//%/\\x}"
}

Note that above urldecode() assumes the data contains no backslash.

Here is similar Joel's version found at: https://github.com/sixarm/urldecode.sh

bash + xxd

Bash function with xxd tool:

urlencode() {
  local length="${#1}"
  for (( i = 0; i < length; i++ )); do
    local c="${1:i:1}"
    case $c in
      [a-zA-Z0-9.~_-]) printf "$c" ;;
    *) printf "$c" | xxd -p -c1 | while read x;do printf "%%%s" "$x";done
  esac
done
}

Found in cdown's gist file, also at stackoverflow.

PHP

Using PHP you can try the following command:

$ echo oil+and+gas | php -r 'echo urldecode(fgets(STDIN));' // Or: php://stdin
oil and gas

or just:

php -r 'echo urldecode("oil+and+gas");'

Use -R for multiple line input.

Perl

In Perl you can use URI::Escape.

decoded_url=$(perl -MURI::Escape -e 'print uri_unescape($ARGV[0])' "$encoded_url")

Or to process a file:

perl -i -MURI::Escape -e 'print uri_unescape($ARGV[0])' file

awk

Try anon solution:

awk -niord '{printf RT?$0chr("0x"substr(RT,2)):$0}' RS=%..

^{Note: Parameter -n is specific to GNU awk.}

Try Stéphane Chazelas urlencode solution:

awk -v RS='&#[0-9]+;' -v ORS= '1;RT{printf("%%%02X", substr(RT,3))}'

See: Using awk printf to urldecode text.

decoding file names

If you need to remove url encoding from the file names, use deurlname tool from renameutils (e.g. deurlname *.*).

See also:

• Can wget decode uri file names when downloading in batch?
• How to remove URI encoding from file names?

Related:

• How to decode URL-encoded string in shell? at SO
• How can I encode and decode percent-encoded strings on the command line? at Ask Ubuntu