Run the named command with its optional command arguments, continuing to run it even after you log out (make command immune to hangups—i.e., no hangup). Terminal output is appended to the file nohup.out by default, or $HOME/nohup.out if nohup.out can’t be written to. Modern shells preserve background commands by default; this command is necessary only in the original Bourne shell.
Print usage information and exit.
Print version information and exit.