What does the bg command do?

The bg command resumes suspended jobs and runs them in the background, allowing you to continue using the terminal while the job executes.

How do I put a job in the background?

First suspend the job with Ctrl+Z, then use 'bg' to resume it in the background, or start a command with '&' to run it in background immediately.

What's the difference between bg and fg?

bg resumes jobs in the background (you can use the terminal), while fg brings jobs to the foreground (job takes control of terminal).

bg Command

The bg command resumes suspended jobs and runs them in the background. It's part of job control in Linux shells, allowing you to manage multiple processes efficiently.

Syntax

bg [job_spec ...]

Description

The bg command places jobs in the background, resuming suspended jobs or continuing stopped jobs. When a job is running in the background, you can continue using the terminal for other commands.

Key features:

Resumes suspended jobs in background
Allows multitasking in terminal
Works with job control
Can specify specific jobs by job ID
Built-in shell command

Job Specification

Format	Description
`%n`	Job number n
`%string`	Job whose command begins with string
`%?string`	Job whose command contains string
`%%` or `%+`	Current job (most recent)
`%-`	Previous job

Examples

Resume most recent suspended job

Resumes the most recently suspended job in the background

Resume specific job by number

bg %1

Resumes job number 1 in the background

Resume multiple jobs

bg %1 %2 %3

Resumes jobs 1, 2, and 3 in the background

Resume job by command name

bg %vim

Resumes the job whose command starts with "vim"

Resume job containing string

bg %?backup

Resumes the job whose command contains "backup"

Complete workflow example

                        # Start a long-running command
                        find / -name "*.log" 2>/dev/null
                        
                        # Press Ctrl+Z to suspend it
                        ^Z
                        [1]+  Stopped    find / -name "*.log" 2>/dev/null
                        
                        # Resume in background
                        bg
                        [1]+ find / -name "*.log" 2>/dev/null &
                        
                        # Check job status
                        jobs
                        [1]+  Running    find / -name "*.log" 2>/dev/null &
                    

Complete example of suspending and resuming a job

Start command directly in background

sleep 300 &

Starts a command directly in background (alternative to bg)

Resume previous job

bg %-

Resumes the previous job (second most recent)

Check all jobs

jobs -l

Lists all jobs with process IDs

Job Control Workflow

Start a command: Run any command normally
Suspend: Press Ctrl+Z to suspend the job
Background: Use bg to resume in background
Check status: Use jobs to see all jobs
Foreground: Use fg to bring job to foreground
Kill: Use kill %n to terminate job