Background processes (&) in Linux CLI - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to run the command sleep 10 in the background.

Linux CLI

sleep 10 [1]

Drag options to blanks, or click blank then click option'

A&

B&&

C|

D;

Attempts:

3 left

💡 Hint

Common Mistakes

Using '&&' runs the next command only if the first succeeds, not backgrounding.

Using '|' pipes output to another command, not backgrounding.

Using ';' runs commands sequentially, not in background.

Adding '&' at the end runs the command in the background, allowing the terminal to accept new commands immediately.

2fill in blank

medium

Complete the code to run ping google.com in the background.

Linux CLI

ping google.com [1]

Drag options to blanks, or click blank then click option'

A&&

B;

C|

D&

Attempts:

3 left

💡 Hint

Common Mistakes

Using '&&' runs the next command only if the first succeeds, not backgrounding.

Using '|' pipes output, not background.

Using ';' runs commands one after another, not background.

The '&' symbol runs the command in the background, freeing the terminal for other commands.

3fill in blank

hard

Fix the error in the command to run ls -l in the background.

Linux CLI

ls -l [1]

Drag options to blanks, or click blank then click option'

A&

B|

C&&

D;

Attempts:

3 left

💡 Hint

Common Mistakes

Using '&&' runs commands conditionally, not background.

Using '|' pipes output, not background.

Using ';' runs commands sequentially, not background.

The '&' symbol correctly runs the command in the background. Other symbols do not background the process.

4fill in blank

hard

Fill both blanks to run sleep 5 in the background and then list jobs.

Linux CLI

sleep 5 [1] [2] jobs

Drag options to blanks, or click blank then click option'

A&

B&&

C;

D|

Attempts:

3 left

💡 Hint

Common Mistakes

Using ';' runs commands sequentially but does not ensure sleep is backgrounded.

Using '|' pipes output, which is not needed here.

Use '&' to run sleep in background, then '&&' to run jobs only after sleep command is started.

5fill in blank

hard

Fill both blanks to run echo Hello in background, then run date only if echo succeeds, finally list jobs.

Linux CLI

echo Hello [1] date [2] jobs ;

Drag options to blanks, or click blank then click option'

A&

B&&

C;

D|

Attempts:

3 left

💡 Hint

Common Mistakes

Using '|' pipes output, which is not needed here.

Using ';' instead of '&&' loses conditional execution.

Use '&' to background echo, '&&' to run date only if echo succeeds, and ';' to run jobs after date.

Practice

1. What does adding & at the end of a command in Linux do?

easy

A. Runs the command with higher priority

B. Stops the command from running

C. Runs the command in the background, freeing the terminal immediately

D. Saves the command output to a file

Solution

1. Step 1: Understand the role of & in Linux commands

   Adding & at the end of a command tells the shell to run it in the background.

2. Step 2: Effect on terminal usability

   Running a command in the background frees the terminal immediately for other commands.

3. Final Answer:

   Runs the command in the background, freeing the terminal immediately -> Option C

4. Quick Check:

   Background process = command + & [OK]

Hint: Remember: & means run in background [OK]

Common Mistakes:

• Thinking & stops the command
• Confusing & with output redirection
• Assuming & increases priority

2. Which of the following is the correct syntax to run sleep 10 in the background?

easy

A. sleep & 10

B. & sleep 10

C. sleep 10 &&

D. sleep 10 &

Solution

1. Step 1: Identify correct placement of &

   The & must be at the end of the command to run it in the background.

2. Step 2: Check each option

   sleep 10 & places & correctly after sleep 10. Others place it incorrectly or use wrong syntax.

3. Final Answer:

   sleep 10 & -> Option D

4. Quick Check:

   Command + & at end = background run [OK]

Hint: Put & at the end of the command [OK]

Common Mistakes:

• Placing & before the command
• Using && instead of &
• Splitting & from command arguments

3. What will be the output after running these commands?

sleep 5 &
jobs

medium

A. Immediately exits the terminal

B. Lists the sleep job running in the background

C. Displays an error about sleep command

D. Shows no jobs running

Solution

1. Step 1: Run sleep 5 &

   This starts the sleep command in the background for 5 seconds.

2. Step 2: Run jobs

   This command lists all background jobs currently running, including the sleep job.

3. Final Answer:

   Lists the sleep job running in the background -> Option B

4. Quick Check:

   jobs shows background tasks [OK]

Hint: Use jobs to see background tasks [OK]

Common Mistakes:

• Expecting jobs to show nothing
• Confusing jobs with ps command
• Thinking sleep runs in foreground without &

4. You ran sleep 10 & but the job does not appear when you run jobs. What is the likely problem?

medium

A. You ran the command in a different shell session

B. The sleep command does not support background execution

C. You forgot to add & at the end

D. The jobs command is not installed

Solution

1. Step 1: Understand job control scope

   Background jobs are tracked per shell session. Running jobs in a different session won't show jobs from another.

2. Step 2: Check other options

   Sleep supports background execution, & was used, and jobs is a built-in command, so those are unlikely issues.

3. Final Answer:

   You ran the command in a different shell session -> Option A

4. Quick Check:

   jobs show current shell's background tasks only [OK]

Hint: jobs only shows current shell's background tasks [OK]

Common Mistakes:

• Assuming jobs shows all system background tasks
• Thinking sleep can't run in background
• Believing jobs is an external command

5. You want to run a script backup.sh in the background and bring it to the foreground later. Which sequence of commands is correct?

hard

A. ./backup.sh & fg %1

B. ./backup.sh && fg

C. ./backup.sh & jobs; fg %2

D. ./backup.sh & bg %1

Solution

1. Step 1: Run the script in background

   Use ./backup.sh & to start the script in the background.

2. Step 2: Bring the background job to foreground

   Use fg %1 to bring job number 1 (the backup script) to the foreground.

3. Step 3: Analyze options

   ./backup.sh & fg %1 correctly runs the script in background and then brings job 1 to foreground. ./backup.sh && fg uses logical && instead of &, so runs in foreground. ./backup.sh & jobs; fg %2 uses wrong job number %2. ./backup.sh & bg %1 uses bg which resumes background jobs, not foreground.

4. Final Answer:

   ./backup.sh & fg %1 -> Option A

5. Quick Check:

   Run with & then fg %job_number to foreground [OK]

Hint: Use fg %job_number to bring background job forward [OK]

Common Mistakes:

• Using && instead of & for background
• Using bg instead of fg to foreground
• Using wrong job number like %2