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VONDS ©

Lab 44: Process Management

Lab Index

Control system responsiveness by moving jobs between the foreground and background, and by lowering CPU priority with nice. Validate your job state and apply priority changes in a controlled, operator-safe way.

troubleshooting core services

Scenario

The server feels sluggish during routine work, and you suspect a combination of interactive shells and CPU-heavy commands are competing for resources. You need to manage job state (foreground vs background) and reduce the priority of a noisy workload so the system stays usable while it runs.

Operator context

Job control keeps you productive in a live shell session. Priority control helps you be a good citizen on shared systems without killing workloads that still need to finish.

Objective

  • Launch a long-running job in the background and confirm it is running.
  • Bring a background job to the foreground and suspend it safely.
  • Resume a suspended job in the background and confirm job state.
  • Start a CPU-heavy workload with reduced priority using nice .

What You’ll Practice

  • Background execution using & and tracking job IDs.
  • Inspecting job state using jobs .
  • Moving jobs between foreground/background with fg and bg .
  • Suspending foreground work with Ctrl+Z .
  • Reducing CPU priority at start time using nice -n .

Walkthrough

Step 1 : Launch a long-running job in the background.
Command 
sleep 60 &

Appending & starts the command in the background and returns you to the prompt. This is useful for long-running commands that do not need your immediate attention. 

Job [1] 1234 running in background.
Step 2 : View background jobs.
Command 
jobs

jobs reports tasks the current shell is tracking. This is job control scope, not a full system process list. 

[1]+  Running                 sleep 60 &
Step 3 : Bring the job to the foreground and suspend it.
Command 
fg %1

fg attaches the job to your terminal again. To pause it without killing it, you can press Ctrl+Z which sends a stop signal and returns control to your shell. 

sleep 60

(user presses Ctrl+Z to suspend it)
[1]+  Stopped                 sleep 60
Step 4 : Resume the job in the background.
Command 
bg %1

bg continues a stopped job but keeps it in the background. This is a clean way to let work finish while you keep using the terminal. 

[1]+ sleep 60 &
Step 5 : Launch a CPU-heavy task with reduced priority.
Safety note

yes will generate endless output. Redirect to /dev/null as shown, and treat this like a test workload you should stop after confirming behavior.

Command 
nice -n 10 yes > /dev/null &

nice starts a process with an adjusted scheduling priority. A higher nice value typically means lower CPU priority. This lets you run heavier workloads while reducing impact on interactive tasks. 

[2] 1245

Reference

  • sleep 60 & : Runs a command in the background and returns to the prompt.
  • jobs : Lists jobs managed by the current shell session.
  • fg %<job> : Brings a job to the foreground (example: fg %1 ).
  • Ctrl+Z : Suspends the current foreground job (stops it without terminating).
  • bg %<job> : Resumes a stopped job in the background.
  • nice -n <value> <command> : Starts a command with adjusted scheduling priority (higher nice typically lowers priority).
  • yes > /dev/null : Generates continuous output redirected to null, commonly used as a simple CPU load test.