Processes

Updated Mar 27, 2021 ·

Tasks

1. Type the command below. Change it from foreground to a background job.

   dd if=/dev/zero of-/dev/null

2. Run the command above for three more times as a background job immediately.

3. Display information about the current background jobs.

4. Change the niceness of one of the dd processes to '-5'.

5. Send a sigkill signal to top.

6. Terminate all dd processes from the command line.

Solution

1. Setting as a background job

Run the command in the foreground:

dd if=/dev/zero of=/dev/null

Suspend the command by pressing Ctrl+Z. Move the suspended job to the background:

bg

2. Run as a background job

Run the command above for three more times as a background job immediately.

dd if=/dev/zero of=/dev/null &
dd if=/dev/zero of=/dev/null &
dd if=/dev/zero of=/dev/null &

3. Display job details

Display information about the current background jobs.

jobs

4. Set the niceness

Find the process ID (PID) of one of the dd processes:

ps aux | grep dd

Change the niceness of the process to -5 (replace <PID> with the actual PID):

sudo renice -5 -p <PID>

5. Kill a job

Send a sigkill signal to top. Run top in the foreground:

top

Find the PID of the top process from another terminal:

pgrep top

Send a SIGKILL signal to the top process (replace <PID> with the actual PID):

kill -9 <PID>

6. Kill processes

Find all dd process IDs:

pgrep dd

Terminate all dd processes:

pkill dd