Understanding the "jobs" Command (with examples)

The “jobs” command is a shell builtin command that is used to view information about processes spawned by the current shell. It allows us to manage and monitor these processes efficiently. In this article, we will explore eight different use cases of the “jobs” command, each showcasing a specific functionality.

View jobs spawned by the current shell

The following command simply displays the jobs spawned by the current shell:

jobs

Motivation: This command is useful when you want to check the status of currently running processes and their job numbers. It helps you monitor the current state of background jobs.

Example Output:

[1]+  Running                 sleep 10 &
[2]-  Running                 find / -name '*.txt' > output.txt &

List jobs and their process IDs

To list jobs along with their process IDs, use the -l option:

jobs -l

Motivation: When you need to identify specific jobs and their associated process IDs, this command is helpful. The process IDs provide a way to uniquely identify and manage individual processes.

Example Output:

[1]+  12345  Running                 sleep 10 &
[2]-  67890  Running                 find / -name '*.txt' > output.txt &

Display information about jobs with changed status

The -n option displays information only about jobs with a changed status:

jobs -n

Motivation: In situations where you have a large number of running jobs and want to focus on those with a changed status, this command comes in handy. It provides a way to quickly identify and manage such jobs.

Example Output:

[1]+  Finished                sleep 10

Display only process IDs

The -p option allows you to display only the process IDs of the jobs:

jobs -p

Motivation: When you need to obtain a list of the process IDs of running or stopped jobs without additional information, this command is useful. The process IDs can be further used for various purposes, such as killing specific processes.

Example Output:

12345
67890

Display running processes

To display only the running processes, use the -r option:

jobs -r

Motivation: This command is handy when you need to focus only on running processes among the existing jobs. It eliminates the need to manually filter out the running processes from the entire list.

Example Output:

[1]+  Running                 sleep 10 &

Display stopped processes

The -s option allows you to display only the stopped processes:

jobs -s

Motivation: When you want to focus only on the stopped processes among the existing jobs, this command becomes essential. It eliminates the need to manually search and identify the stopped processes.

Example Output:

[2]-  Stopped                 find / -name '*.txt' > output.txt

Conclusion

The “jobs” command is a powerful tool for managing and monitoring processes spawned by the current shell. With its various options, such as displaying different statuses or obtaining process IDs, it provides greater control and transparency when working with multiple background jobs.

Remember to refer to the official documentation for more information on the command and its exclusive options available in bash.