"jobs" - Manage Background Jobs

Provides a tutorial example on how to use 'jobs' command to display background jobs, which are processes with input detached the keyboard. You can start a background job by adding the 'ampersand' sign to the end of the commmad.

What Is Background Job? - A background job is a process with its input being detached from the keyboard device. Its output may still be attached to the screen.

A foreground job is a process with its input being attached to the keyboard device. When you enter a command at the shell prompt to start a process, it will be started as a foreground job by default. The keyboard will be occupied by this foreground job until it is terminated. So you can only executed 1 process job at any time.

If you want start a process as a background job to keep the keyboard free for the next process, you use the following 2 options:

1. Adding "&" at the end of the command line. This will start the process as a background job immediately. For example, the following command starts a process (ID=40120) as a background job (#=1).

herong$ sleep 100000 &
[1] 40120

2. Press "ctrl-z" during the execution of a foreground job. This will stop the foreground job and make it as a background job and keep it as stopped.

herong$ sleep 50000
ctrl-z
[2]+  Stopped                 sleep 50000

If you want to see a list of your own background jobs, you can use the "jobs" command:

herong$ jobs
[1]-  Running                 sleep 100000 &
[2]+  Stopped                 sleep 50000

If you want to resume a stopped job in the background, you can use the "bg #" command:

herong$ bg 2
[2]+ sleep 50000 &

herong$ jobs
[1]-  Running                 sleep 100000 &
[2]+  Running                 sleep 50000 &

If you want to bring a background job to the foreground, you can use the "fg" command:

herong$ fg 2
sleep 100000

One nice about running a command in the background is that it will to run, even if your shell session gets disconnected/closed.

Table of Contents

 About This Book

 Introduction to Linux Systems

 Cockpit - Web Portal for Administrator

Process Management

 "ps" - Display Current Processes

"jobs" - Manage Background Jobs

 "tmux" - Terminal Multiplexer

 Files and Directories

 Users and Groups

 File Systems

 Installing CentOS

 SELinux - Security-Enhanced Linux

 Network Connection on CentOS

 Software Package Manager on CentOS - DNF and YUM

 Running Apache Web Server (httpd) on Linux Systems

 Running PHP Scripts on Linux Systems

 Running MySQL Database Server on Linux Systems

 Running Python Scripts on Linux Systems

 vsftpd - Very Secure FTP Daemon

 Postfix - Mail Transport Agent (MTA)

 Dovecot - IMAP and POP3 Server

 Email Client Tools - Mail User Agents (MUA)

 GCC - C/C++ Compiler

 Conda - Environment and Package Manager

 Tools and Utilities

 References

 Full Version in PDF/EPUB