A little something to prevent hanging greps

gistfile1.rb

#!/usr/bin/env ruby                                                             
query = $*.shift
if $*.empty? && $stdin.tty?
  puts "You haven't given grep anything"
else
  cmd = %(grep "#{query}" #{$*.join(' ')})
  puts `#{cmd}`
end

Nice! Probably more portable in bash, I think:

function fancy-grep() {
  local query="$1"; shift
  if [[ -z "$@" ]] && [[ -t 0 ]]; then
    echo "You haven't given grep anything." >&2
  else
    /bin/grep "$query" "$@"
  fi
}