Background processes play a vital role in optimizing system resources and improving productivity. Learning how to run processes in the background can help you efficiently manage tasks and make your workflow more seamless.

Overview

When executing commands or running scripts in a terminal session, each process has its own execution flow. A foreground process takes control of the terminal until it completes, while a background process runs independently without blocking the current session.

Benefits of Running Processes in Background:

Running processes in the background offers several advantages.

  1. Uninterrupted Workflow: You can continue working on other tasks while long-running programs execute silently.
  2. Resource Optimization: Background processes consume fewer system resources by avoiding unnecessary blocking.
  3. Automating Tasks: By executing scripts or commands as background processes, you can schedule them at specific times or intervals.

Running Processes in Background:

1: Using ‘&’ symbol

The easiest way to run a command or script as a background process is to append an & symbol at the end of the command.

./myscript.sh &

2: Ctrl + Z & ‘bg’ Command

Another approach is to pause a foreground process by pressing Ctrl + Z and then resume it as a background task using the bg command.

  1. Start a foreground task: ./script.sh
  2. Hit ‘Ctrl + Z’ to pause it.
  3. Run bg command to restart it as a background process.

To demonstrate this, below is the script for validation. This script prints messages and in between it sleeps for 1 minute. So, we have to check below steps within minute of starting it.

1#!/bin/bash
2echo "Starting"
3sleep 1m
4echo "Finished"

Start script using ./script.sh. Hit Ctrl + Z to pause it. Type bg to restart in background. At this point, the script is running in the background. You can check it running using ps -ef | grep script.sh command. After about a minute, you will see “Finished” message on the terminal along with message like below.

[1]+  Done                    ./script.sh

Monitoring Background Processes:

To view all active background processes at any time, use the jobs command.

Additionally, you can bring a background process to the foreground using the fg command, allowing you to interact with it again.

  • jobs - Lists all active background processes.
  • fg <job> - Brings a specific background process to the foreground.
  • bg <job> - Resumes a paused process in the background.

Alternatively, we can use ps -ef to check running processes and grep for specific process that we want to monitor.