nohup is a command which helps us to run any command immune to hang ups. Assume that we run a command and it takes a long time to finish. If you log out while it is running the process will be terminated. If we want a command to run even if we log out then nohup can be used.
We can use nohup like this
nohup mylongrunningprogram >logfile &
nohup mylongrunningprogram &
nohup : the command
mylongrunningprogram: the command we want to run
> logfile : redirect standard out messages to a file named logfile.
If not specified output will be stored in nohup.out (as used in the second example above)
& : run the process in the background