Decoding URL encoding (percent encoding)

Found these Python one liners that do what you want:

$ alias urldecode='python -c "import sys, urllib as ul; \
    print ul.unquote_plus(sys.argv[1])"'

$ alias urlencode='python -c "import sys, urllib as ul; \
    print ul.quote_plus(sys.argv[1])"'

Example

$ urldecode 'q+werty%3D%2F%3B'
q werty=/;

$ urlencode 'q werty=/;'
q+werty%3D%2F%3B

References

• Urlencode and urldecode from a command line

And another Perl approach:

#!/usr/bin/env perl
use URI::Encode;
my $uri     = URI::Encode->new( { encode_reserved => 0 } );
while (<>) {

    print $uri->decode($_)
}

You will need to install the URI::Encode module. On my Debian, I could simply run

sudo apt-get install URI::Encode

Then, I ran the script above on a test file containing:

http://foo%21asd%23asd%24%26asd%27asd%28asd%29

The result was (I had saved the script as foo.pl):

$ ./foo.pl
http://foo!asd#asd$&asd'asd(asd)

If you want to simple use sed command then use following command:

sed -e 's/%21/!/g' -e 's/%23/#/g' -e 's/%24/$/g' -e 's/%26/&/g' -e s/%27/"'"/g -e 's/%28/(/g' -e 's/%29/)/g'

But is is more convenient to create script like (say sedscript):

#!/bin/bash
s/%21/!/g
s/%23/#/g
s/%24/$/g
s/%26/&/g
s/%27/"'"/g
s/%28/(/g
s/%29/)/g

Then run sed -f sedscript <old >new which will out-put as you desired.

There is a built-in function for that in the Python standard library. In Python 2, it's urllib.unquote.

decoded_url=$(python2 -c 'import sys, urllib; print urllib.unquote(sys.argv[1])' "$encoded_url")

Or to process a file:

python2 -c 'import sys, urllib; print urllib.unquote(sys.stdin.read())' <file >file.new &&
mv -f file.new file

In Python 3, it's urllib.parse.unquote.

decoded_url=$(python2 -c 'import sys, urllib.parse; print(urllib.parse.unquote(sys.argv[1]))' "$encoded_url")

Or to process a file:

python3 -c 'import sys, urllib; print(urllib.parse.unquote(sys.stdin.read()))' <file 

file.new && mv -f file.new file

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

If you want to stick to POSIX portable tools, it's awkward, because the only serious candidate is awk which doesn't parse hexadecimal numbers. see Using awk printf to urldecode text for examples with common awk implementations including BusyBox.

Perl one liner:

$ perl -pe 's/\%(\w\w)/chr hex $1/ge'

Example:

$ echo '%21%22' |  perl -pe 's/\%(\w\w)/chr hex $1/ge'
!"