Jobs command example

Jobs command example

I am a new Linux/Unix user. In Linux or Unix-like systems, how can I use BASH/KSH/TCSH or POSIX-based shell to view the job in progress )? On Unix/Linux, how does one display the current job status? (LCTT: job, also known as "task ")

Job control is a capability that can stop/pause the execution of processes (commands) and continue/resume their execution as required. This is executed through your operating system and shell such as bash/ksh or POSIX shell.

Shell stores the currently executed jobs in a table and can be displayed using the jobs command.

 

Purpose

Displays the job status in the Current shell session.

 

Syntax

The basic syntax is as follows:

1. jobs

Or

1. jobs jobID

Or

1. jobs [options] jobID

 

Start some jobs for demonstration

Before using the jobs command, you must start multiple jobs on the system. Run the following command to start the job:

1. ### Start xeyes, calculator, and gedit text editor ###
2. xeyes &
3. gnome-calculator &
4. gedit fetch-stock-prices.py &

Finally, run the ping command on the foreground:

1. ping www.cyberciti.biz

Press Ctrl-Z to suspend the (suspend) ping command job.

 

Jobs command example

To display the job status in the current shell, enter:

1. $ jobs

Output example:

1. [1]7895Running gpass &
2. [2]7906Running gnome-calculator &
3. [3]-7910Running gedit fetch-stock-prices.py &
4. [4]+7946Stoppedping cyberciti.biz

To display the process ID or job name whose name starts with "p", enter:

1. $ jobs -p %p

Or

1. $ jobs %p

Output example:

1. [4]-Stoppedping cyberciti.biz

Character % is a method for specifying a task. In this example, you can use a string starting with the job name to pause it, for example, % ping.

 

How does one display that the process ID does not contain other normal information?

Use the-l (lower-case L) option of the jobs command to list the details of each job. Run:

1. $ jobs -l

Sample output:

Fig.01: display the jobs status in shell

 

How to list only the processes with the last state change?

First, start a new job as follows:

1. $ sleep100&

Now, only jobs that have been stopped or exited since the last time are displayed. Enter:

1. $ jobs -n

Sample output:

1. [5]-Runningsleep100&

 

Show only process ID (PID)

The-p option of the jobs command only displays PID:

1. $ jobs -p

Sample output:

1. 7895
2. 7906
3. 7910
4. 7946
5. 7949

 

How can I only display running jobs?

The-r option of the jobs command only displays running jobs. Enter:

1. $ jobs -r

Sample output:

1. [1]Running gpass &
2. [2]Running gnome-calculator &
3. [3]-Running gedit fetch-stock-prices.py &

 

How to show only jobs that have stopped working?

Use the-s option of the jobs command to display only the jobs that stop the job. Enter:

1. $ jobs -s

Sample output:

1. [4]+Stoppedping cyberciti.biz

To continue to run the ping cyberciti. biz job, enter the following bg command:

1. $ bg %4

 

Jobs Command Option

From the bash (1) command man manual page:

Option	Description
-l	Lists process IDs and other information.
-p	Only process IDs are listed.
-n	Only lists the processes with status changes that have occurred since the last time the Status Change Prompt (for example, a process exits) is displayed.
-r	Only running jobs are displayed.
-s	Only the stopped jobs are displayed.
-x	Run the command and its parameters, and replace the process group ID of the matched original job with the process ID of the new command.

 

Description of/usr/bin/jobs and shell built-in

Run the following type command to check whether the jobs command is a shell built-in command or an external command is still:

1. $ type -a jobs

Output example:

1. jobs is a shell builtin
2. jobs is/usr/bin/jobs

In almost all cases, you need to use the built-in jobs command of BASH/KSH/POSIX shell. The/usr/bin/jobs command cannot be used in the current shell. The/usr/bin/jobs command works in different environments and does not share shell jobs of its parent bash/ksh.

Via: http://www.cyberciti.biz/faq/unix-linux-jobs-command-examples-usage-syntax/

Author: Vivek Gite Translator: strugglingyouth Proofreader: wxy

This article was originally compiled by LCTT and launched with the honor of Linux in China

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