bin/url-unshorten

#!/usr/bin/env bash
# From https://github.com/benjaminoakes/utilities
set -o errexit

function show-usage {
  cat <<EOF
Usage: $0 [--help] [url | [[-f | --file] path]]

Map shortened URLs to their expanded versions.

  --help        Show this help text.
  url           A single URL to resolve.
  path          File containing URLs to resolve, one per line.

Example:

  $ $0 http://t.co/asdf
  http://t.co/foo => http://example.com/

  $ cat file.txt
  http://t.co/foo
  http://t.co/bar
  $ $0 --file file.txt
  http://t.co/foo => http://example.com/baz
  http://t.co/bar => http://example.com/qux
EOF
  exit -1
}

function resolve {
  url="$1"

  echo -n "$url => "
  curl --verbose "$url" 2>&1 |
    grep 'Location: ' |
    sed 's/< Location: //'
}

# TODO: also accept URL as parameter so it doesn't have to be in a file
if [ "$1" == '--help' -o "$1" == '' ]; then
  show-usage
fi

if [ "$1" == '-f' -o "$1" == '--file' ]; then
  for url in $(cat $2); do
    resolve "$url"
  done
else
  resolve "$1"
fi