jobs Command: Tutorial & Examples
The jobs command is an essential part of a shell user's toolbox. Its primary function is to
display the status of jobs in the current session. This command becomes particularly useful when you are dealing with
background processes or multiple tasks within a single terminal.
What jobs Does and Why It's Important
When you're working on a Linux server or VM, you often need to perform multiple tasks simultaneously. These tasks can be
run in the background, freeing up your terminal for other work. Here's where the jobs command comes in - it allows you
to view and control these background tasks.
Running a jobs command lists the tasks currently being executed in the background, along with their statuses. This can
help you monitor the progress of these tasks and manage them effectively.
Understanding How jobs Works
The jobs command works with the shell, specifically the bash shell's job control function. When
you run a command or process in the background, the shell assigns it a job ID. The jobs command
uses these job IDs to list, manage and control these jobs.
How to Use jobs
Using jobs is straightforward. Here are a few examples:
$ sleep 100 &
$ jobs
[1]- Running sleep 100 &
In the first line, we're running the sleep command in the background. The jobs command will
then list this background job with its status and job ID.
Common Command Line Parameters
There are several options you can use with jobs:
-l: Provides more detailed information, including the process ID (PID).-n: Only shows jobs that have changed status since the last notification.-p: Only display PID.-r: Show only running jobs.-s: Show only stopped jobs.
Example with parameters:
$ sleep 100 &
$ jobs -l
[1] 1234 Running sleep 100 &
This example displays the PID (1234 in this case) thanks to the -l option.
Potential Problems and Pitfalls
While jobs is a useful command, it's important to understand its limitations. The jobs command only works in the
current shell session. If you start a new terminal session or log out, the jobs in the previous session won't be
accessible.
Also, the jobs command works with the jobs started in the current shell. It doesn't show system-wide processes or jobs
started in other sessions. For these tasks, use commands like top or ps.
Conclusion
The jobs command is a powerful tool for managing tasks within a shell session. It allows you to view the status of
background tasks, giving you better control over your Linux server or VM. While it has its limitations, understanding
how to use jobs effectively can significantly enhance your productivity when working with Linux servers.
