ShellCheck for static analysis in Bash Scripting - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What does ShellCheck report for this script?

Given the following Bash script, what warning or error will ShellCheck produce?

Bash Scripting

echo "User input is: $1"
if [ $1 -eq 10 ]; then
  echo "Input is ten"
fi

A SC1009: The mentioned syntax error was in this if statement.

B No warnings, script is clean.

C SC2086: Double quote to prevent globbing and word splitting.

D SC2154: $1 is referenced but not assigned.

💡 Hint

ShellCheck often warns about unquoted variables in test conditions.

ShellCheck warns that $1 should be quoted in the test to avoid word splitting or globbing issues.

📝 Syntax

intermediate

Which script will pass ShellCheck without errors?

Select the Bash script snippet that will NOT produce any ShellCheck warnings or errors.

A for file in *.txt; do echo ${file}; done; echo $file

B for file in *.txt; do echo "$file"; done

C for file in *.txt; do echo ${file}; done

D for file in *.txt; do echo $file; done

💡 Hint

ShellCheck warns about unquoted variables that may cause word splitting.

Option B quotes the variable properly, avoiding word splitting and globbing issues.

🔧 Debug

advanced

Identify the ShellCheck warning for this script

What specific ShellCheck warning will this script produce?

Bash Scripting

#!/bin/bash

read -p "Enter your name: " name
if [ "$name" = "" ]; then
  echo "No name entered"
fi

A SC2143: Use grep -q instead of comparing output with -eq.

B No warnings, script is clean.

C SC2006: Use $(...) instead of backticks.

D SC2162: read without -r will mangle backslashes.

💡 Hint

ShellCheck warns about read command usage without -r option.

ShellCheck recommends using read -r to prevent backslash escapes from being interpreted.

🧠 Conceptual

advanced

Why does ShellCheck warn about this variable usage?

Consider this snippet: filename=$1 if [ -f $filename ]; then echo "File exists" fi Why does ShellCheck warn about the test condition?

A Because $filename is unquoted, it may cause word splitting or globbing issues.

B Because $filename is not declared as a local variable.

C Because -f test requires an absolute path, not a variable.

D Because the if statement syntax is incorrect.

💡 Hint

Think about what happens if the filename contains spaces.

ShellCheck warns that unquoted variables in tests can cause unexpected behavior if the variable contains spaces or special characters.

🚀 Application

expert

What is the output of running ShellCheck on this script?

Given this script: #!/bin/bash for i in {1..3} do echo "Number: $i" done What output will ShellCheck produce?

A No warnings or errors, script is clean.

B SC2034: i appears unused in the loop.

C SC1009: Syntax error near unexpected token '{1..3}'.

D SC2086: Double quote to prevent globbing and word splitting.

💡 Hint

Brace expansion is valid in Bash and commonly used in loops.

The script uses valid brace expansion and quotes the variable properly, so ShellCheck reports no issues.