Command chaining (&&, ||, ;) in Linux CLI - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this chained command?

Consider the following command run in a Linux shell:

echo Hello && echo World || echo Fail

What will be printed?

Linux CLI

echo Hello && echo World || echo Fail

A Hello\nWorld

B Hello\nFail

C World

D Fail

💡 Hint

Remember that && runs the next command only if the previous succeeds, and || runs the next command only if the previous fails.

The first echo prints 'Hello' and succeeds, so the second echo runs and prints 'World'. Since the second command succeeds, the || part does not run.

💻 Command Output

intermediate

What happens with semicolon chaining?

What is the output of this command?

echo Start; false; echo End

Note: 'false' is a command that always fails.

Linux CLI

echo Start; false; echo End

A End

B Start

C Start\nEnd

D Start\nfalse\nEnd

💡 Hint

Semicolon runs all commands regardless of success or failure.

Semicolon separates commands to run one after another no matter what. So 'Start' prints, then 'false' runs (fails silently), then 'End' prints.

💻 Command Output

advanced

What is the output of this mixed chaining?

What will this command print?

false && echo No || echo Yes; echo Done

Linux CLI

false && echo No || echo Yes; echo Done

A Yes\nDone

B No\nDone

C No

D Done

💡 Hint

&& runs next only if previous succeeds; || runs next only if previous fails; semicolon always runs next.

false fails, so 'echo No' after && does not run. The || runs 'echo Yes'. Then semicolon runs 'echo Done'.

💻 Command Output

advanced

What error or output occurs here?

What happens when running this command?

mkdir test_dir && cd test_dir || echo Failed

Linux CLI

mkdir test_dir && cd test_dir || echo Failed

A cd: no such file or directory: test_dir

B No output, current directory changes to test_dir

C mkdir: cannot create directory ‘test_dir’: File exists

D Failed

💡 Hint

If mkdir succeeds and cd succeeds, || echo Failed does not run.

If 'test_dir' does not exist, mkdir creates it and succeeds, cd changes directory successfully, so echo Failed does not run and no output appears.

💻 Command Output

expert

What is the output of this complex chain?

Analyze this command:

echo Start && false || echo Middle && echo End

What will be printed?

Linux CLI

echo Start && false || echo Middle && echo End

A Start\nMiddle

B Middle\nEnd

C Start\nEnd

D Start\nMiddle\nEnd

💡 Hint

Remember operator precedence: && has higher precedence than ||, so group accordingly.

The command groups as: (echo Start && false) || (echo Middle && echo End). 'echo Start' succeeds, then 'false' fails, so left side fails. Right side runs: 'echo Middle' prints, succeeds, so 'echo End' runs and prints.