bg command in Linux

The bg command in Linux is used to resume a suspended job and run it in the background. It allows processes to continue execution without blocking the terminal.

• Moves a stopped (suspended) job to the background
• Works with job control in the shell (like Bash)
• Requires a job ID (e.g., bg %1) to resume a specific job
• Commonly used after suspending a process using Ctrl + Z
• Allows the terminal to be used for other commands while the job runs

Example

Step 1: Start a long-running process (e.g., sleep 60).

sleep 60

Step 2: Suspend the process by pressing Ctrl + Z.

Output:

[1]+  Stopped                 sleep 60

Step 3: Resume the suspended process in the background using bg.

bg

Output:

[1]+ sleep 60 &

• The process sleep 60 resumes execution in the background.
• You can verify it by running the jobs command:

Syntax

bg [job_spec ...]

where,

• job_spec: This is used to identify the job you want to move to the background. It can be specified in several formats:
• %n: Refers to job number n.
• %str: Refers to a job that was started by a command beginning with str.
• %?str: Refers to a job that was started by a command containing str.
• %% or %+: Refers to the current job. Both fg and bg commands will operate on this job if no job_spec is provided.
• %-: Refers to the previous job.

If no job_spec is provided, the most recent job is resumed in the background.

Useful Options for bg command

1. bg [JOB_SPEC]:

This command is used to run the mentioned job in the background.

Command:

jobs
sleep 500
# Press: Ctrl + Z   (to suspend the process)

jobs
bg %1
jobs

Output:

The command sleep 500 creates a foreground job.

• We use jobs command to list all jobs
• We create a process using sleep command, we get its ID as 1.
• We move it to the background using its job ID with bg

2. bg --help:

Displays the help information for the bg command. This is useful if you need more information.

Command:

bg --help

Output: