CLI Process Management

Introduction

Every time you run a command on the command line, it has to run for some period of time. Linux knows how to get the resources that the program needs to run for its lifetime. The command and its resources are called a 'process'. So, a process is just something that is running on your system. Processes aren't limited to programs that you've started on the command line, everything running on your system is a process, including BASH. Linux manages these processes and you have the ability to interact with them using the command line.

Commands

xeyes = A silly program that displays a graphic depicting a set of eyes that follow your mouse pointer.

fg = Put a process into the foreground
bg = Put a process into the background

Ctrl+z = Suspend a process

ps   = List the processes running on your system
jobs = List the jobs executing in this terminal's context

kill = Send a signal to a process

&    = Indicates that a process is running in the background

Examples

1. Execute 'xeyes -color red'
2. Click on the terminal to give it the focus
3. Press <Ctrl-z> (this will suspend the application, notice the eyes are no longer following the mouse)
4. Execute 'xeyes -color red'
5. Click on the terminal to give it the focus
6. Press '<Ctrl>+z'
7. Execute 'jobs'
8. Execute 'bg %1' (Notice that the red eyes are now following your cursor and that the terminal is available to you)

Quiz

1. Launch the 'emacs' program in the background.
2. Put it into the foreground.
3. Suspend it.
4. Restart it in the background.
5. Kill it.