Shell steps (sh, bat) in Jenkins - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this Jenkins shell step?

Consider this Jenkins pipeline shell step using sh to list files. What will be the output if the workspace contains files file1.txt and file2.txt?

Jenkins

sh 'ls *.txt'

A file1.txt file2.txt

B No output, command fails

C ls: cannot access '*.txt': No such file or directory

D

file1.txt
file2.txt

💡 Hint

Think about how the shell expands wildcards and how Jenkins captures output.

The sh step runs the shell command and outputs matching files each on a new line.

❓ Troubleshoot

intermediate

Why does this Jenkins bat step fail on Windows agent?

This Jenkins pipeline step runs a Windows batch command but fails with 'command not found'. What is the likely cause?

Jenkins

bat 'echo Hello World'

A The <code>echo</code> command is misspelled

B The agent is Linux, so <code>bat</code> commands won't run

C The Jenkinsfile syntax is incorrect for <code>bat</code>

D The workspace path is invalid

💡 Hint

Consider the environment where the command runs.

The bat step runs Windows batch commands and requires a Windows agent. On Linux agents, it fails.

❓ Configuration

advanced

How to capture output of a shell step in Jenkins pipeline?

You want to save the output of a shell command into a variable in a Jenkins pipeline scripted syntax. Which snippet correctly captures the output?

A def result = sh(script: 'date')

B def result = bat(script: 'date', returnStdout: true)

C def result = sh(script: 'date', returnStdout: true).trim()

D def result = sh('date')

💡 Hint

Look for the option that returns command output as a string.

The sh step with returnStdout: true returns the command output as a string.

✅ Best Practice

advanced

Which approach is best for cross-platform shell steps in Jenkins pipeline?

You want to write a Jenkins pipeline that runs shell commands on both Linux and Windows agents. Which approach is best?

A Use <code>sh</code> step for Linux and <code>bat</code> step for Windows inside <code>if</code> condition checking OS

B Use only <code>sh</code> step for all agents

C Use only <code>bat</code> step for all agents

D Write commands in Groovy without shell steps

💡 Hint

Think about agent OS compatibility.

Using sh for Linux and bat for Windows with OS checks ensures commands run correctly on each platform.

🔀 Workflow

expert

Order the steps to run a shell command, capture output, and archive a file in Jenkins pipeline

Arrange these Jenkins pipeline steps in the correct order to run a shell command, save its output, and archive a file named output.log:

A 1,3,2,4

B 3,1,2,4

C 1,2,3,4

D 2,1,3,4

💡 Hint

Think about creating the file before reading and archiving it.

First create the file with shell command (1), then read it (3), archive it (2), and finally print confirmation (4).

Practice

1. In Jenkins pipelines, which shell step should you use to run a command on a Linux agent?

easy

A. bat

B. sh

C. cmd

D. powershell

Solution

1. Step 1: Understand Jenkins shell steps

   Jenkins uses sh to run shell commands on Linux/macOS agents.

2. Step 2: Identify the correct shell for Linux

   Since Linux uses bash or sh shells, sh is the correct step.

3. Final Answer:

   sh -> Option B

4. Quick Check:

   Linux shell step = sh [OK]

Hint: Use sh for Linux/macOS, bat for Windows agents [OK]

Common Mistakes:

• Using bat on Linux agents
• Confusing cmd with sh
• Using powershell on non-Windows agents

2. Which of the following is the correct syntax to run a Windows batch command in a Jenkins pipeline?

easy

A. sh 'dir'

B. cmd 'dir'

C. powershell 'dir'

D. bat 'dir'

Solution

1. Step 1: Identify Windows shell step in Jenkins

   Jenkins uses bat to run Windows batch commands.

2. Step 2: Match syntax for batch command

   The correct syntax is bat 'command', so bat 'dir' is correct.

3. Final Answer:

   bat 'dir' -> Option D

4. Quick Check:

   Windows batch command = bat [OK]

Hint: Use bat for Windows commands in Jenkins pipelines [OK]

Common Mistakes:

• Using sh for Windows commands
• Using cmd which is not a Jenkins step
• Using powershell without proper syntax

3. What will be the output of this Jenkins pipeline snippet on a Linux agent?

sh 'echo Hello Jenkins'

medium

A. Hello Jenkins

B. sh: command not found

C. echo Hello Jenkins

D. Syntax error

Solution

1. Step 1: Understand the sh step execution

   The sh step runs the command inside quotes on the Linux shell.

2. Step 2: Predict command output

   The command echo Hello Jenkins prints the text 'Hello Jenkins' to the console.

3. Final Answer:

   Hello Jenkins -> Option A

4. Quick Check:

   sh echo outputs text [OK]

Hint: sh runs commands and prints their output on Linux [OK]

Common Mistakes:

• Expecting the command itself as output
• Confusing syntax error with correct command
• Assuming sh step fails on Linux

4. You wrote this Jenkins pipeline step:

bat 'echo Hello from Linux'

But it runs on a Linux agent and fails. What is the problem?

medium

A. bat is for Windows, not Linux

B. echo command is invalid

C. Missing quotes around command

D. Pipeline syntax error

Solution

1. Step 1: Identify shell step and agent OS mismatch

   The bat step runs Windows batch commands, but the agent is Linux.

2. Step 2: Understand why failure occurs

   Linux agents do not support bat, so the step fails.

3. Final Answer:

   bat is for Windows, not Linux -> Option A

4. Quick Check:

   bat step on Linux = failure [OK]

Hint: Match shell step to agent OS: bat=Windows, sh=Linux [OK]

Common Mistakes:

• Thinking echo is invalid on Linux
• Assuming quotes cause error
• Blaming pipeline syntax instead of shell step

5. You want to write a Jenkins pipeline that runs a shell command on both Windows and Linux agents. Which approach is best?

hard

A. Use sh step for all agents

B. Use bat step for all agents

C. Use sh for Linux and bat for Windows with if condition

D. Use powershell step for all agents

Solution

1. Step 1: Recognize OS differences in shell steps

   Linux agents require sh, Windows agents require bat.

2. Step 2: Use conditional logic in pipeline

   Use an if condition to detect OS and run the correct shell step.

3. Final Answer:

   Use sh for Linux and bat for Windows with if condition -> Option C

4. Quick Check:

   Conditional shell steps match OS [OK]

Hint: Use if condition to select sh or bat by OS [OK]

Common Mistakes:

• Using one shell step for all OSes
• Ignoring agent OS detection
• Using powershell without Windows-only context