Run a Unix process in the background

In Unix, a background process executes independently of the shell, leaving the terminal free for other work. To run a process in the background, include an & (an ampersand) at the end of the command you use to run the job. Following are some examples:

• To run the count program, which will display the process identification number of the job, enter:

   count &

• To check the status of your job, enter:

   jobs

• To bring a background process to the foreground, enter:

   fg

• If you have more than one job suspended in the background, enter:

   fg %#

  Replace # with the job number, as shown in the first column of the output of the jobs command.

• You can kill a background process by entering:

   kill PID

  Replace PID with the process ID of the job. If that fails, enter the following:

   kill -KILL PID

• To determine a job's PID, enter:

   jobs -l

• If you are using sh, ksh, bash, or zsh, you may prevent background processes from sending error messages to the terminal. Redirect the output to /dev/null using the following syntax:

   count 2> /dev/null &