I was trying to use the tool goorecon and I get the error

bash: ./goorecon.rb: /usr/bin/ruby^M: bad interpreter: No such file or directory

So I checked /usr/bin and ruby is there

root@bt:/pentest/enumeration/goorecon# ls -al /usr/bin | grep ruby
lrwxrwxrwx  1 root   root           7 Jan 22 11:57 ruby -> ruby1.8
-rwxr-xr-x  1 root   root        6320 Sep 26  2008 ruby-glade-create-template
-rwxrwxrwx  1 root   root        5432 Jul 16  2009 ruby1.8

other .rb work just fine.