Understanding Shell Job Control

The command line provides the powerful ability to stop (suspend) the execution of a process and resume a suspended process at a later point in time. Each running program is referred to as a job, and a unique ID is assigned to every job for easy management.

Key Job Control Commands

Here's a breakdown of essential commands for managing your shell jobs:

Command	Description
jobs	Lists all the jobs that the current shell is running or has suspended.
fg	Brings a suspended or background job to the foreground for interactive use.
bg	Sends a suspended job to the background, allowing you to continue using the terminal.
kill	Terminates a specified job.
stop	Suspends the execution of a running job.
Ctrl+c	Interrupts and terminates the currently running foreground job.
Ctrl+z	Suspends the currently running foreground job, sending it to the background.

Running Jobs in the Background

To start a job in the background immediately, append an ampersand (&) to the end of your command.

Examples of Job Control Usage

• Start a job in the background:
  sleep 1000 &
• Bring a job to the foreground:
  fg %2 # where 2 is the job number
• Suspend a running job:
  stop %2 # where 2 is the job number
• Resume a suspended job in the background:
  bg %2 # where 2 is the job number
• Terminate a job:
  kill %2 # where 2 is the job number

Further Reading on Process Management

For a deeper understanding of how processes and job control work in Unix-like systems, you can refer to the following resources:

• jobs man page
• fg man page
• bg man page
• kill man page
• Bash Job Control Documentation