urldecode [OPTIONS] [STRING_TO_ENCODE]
urldecode is a simple command line utility to URL decode content. By default it reads from standard input and writes to standard out. You can also specifty the string to decode as a command line parameter.
-h display help
-help display help
-i set input filename
-input set input filename
-l display license
-license display license
-o set output filename
-output set output filename
-q use query escape (pluses for spaces)
-query use query escape (pluses for spaces)
-v display version
-version display version
echo 'This%20is%20the%20string%20to%20encode%20&%20nothing%20else%0A' | urldecode
would yield
This is the string to encode & nothing else!