nohup for persistent processes in Linux CLI - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this nohup command?

You run the command nohup sleep 10 & in a terminal. What will be the immediate output shown in the terminal?

Linux CLI

nohup sleep 10 &

A nohup: ignoring input and appending output to 'nohup.out'

B sleep: command not found

C No output, just returns to prompt immediately

D Error: nohup requires a command argument

💡 Hint

Think about what nohup does with output when running a command in background.

The nohup command detaches the process from the terminal and redirects output to 'nohup.out' by default, printing a message about ignoring input and appending output.

🧠 Conceptual

intermediate

Why use nohup with background processes?

Which of the following best explains why you use nohup when running a process in the background?

A To run the process with higher priority

B To speed up the process execution by using more CPU cores

C To keep the process running even after the terminal is closed or you log out

D To automatically restart the process if it crashes

💡 Hint

Think about what happens to normal background processes when you close the terminal.

nohup prevents the process from receiving the hangup signal (SIGHUP) when the terminal closes, so the process keeps running.

🔧 Debug

advanced

Why does this nohup command fail to keep process running?

You run nohup python myscript.py and then close the terminal, but the script stops immediately. What is the most likely reason?

Linux CLI

nohup python myscript.py

A nohup only works with compiled binaries, not scripts

B You forgot to add & to run it in background

C The script reads input from terminal and blocks, causing it to stop

D The script has a syntax error and exits immediately

💡 Hint

Think about how to run commands in background with nohup.

Without & the command runs in foreground and closing terminal sends SIGHUP, stopping the process.

📝 Syntax

advanced

Which command correctly runs a persistent process with nohup and redirects output?

Choose the correct command to run myapp persistently with nohup, sending all output to app.log and running in background.

A nohup myapp & 2>&1 > app.log

B nohup myapp & > app.log 2>&1

C nohup myapp 2>&1 > app.log &

D nohup myapp > app.log 2>&1 &

💡 Hint

Remember the order of output redirection and background symbol matters.

Option D correctly redirects stdout and stderr to app.log and runs the process in background.

🚀 Application

expert

How many lines will nohup.out contain after running this command?

You run nohup bash -c 'for i in {1..5}; do echo $i; sleep 1; done' and wait until it finishes. How many lines will the nohup.out file contain?

A 5

B 0

C 1

D 10

💡 Hint

Each echo prints one line, and output goes to nohup.out by default.

The loop prints numbers 1 to 5, each on its own line, so nohup.out will have 5 lines.