daemon-env.rb

#!/usr/bin/env ruby

$0 = 'daemon-env'
loop {}

daemon-ruby.rb

#!/usr/local/ruby/bin/ruby

$0 = 'daemon-ruby'
loop {}

gistfile1.txt

% ./daemon-env.rb &
[1] 10875
% ./daemon-ruby.rb &
[2] 10877
% pgrep daemon-env
% pgrep daemon-ruby
10877
% ps -o 'pid,ucomm,command'
  PID COMMAND         COMMAND
10784 zsh             -zsh
10875 ruby            daemon-env          
10877 daemon-ruby.rb  daemon-ruby                              
10881 ps              ps -o pid,ucomm,command