[[ ]] extended test in Bash Scripting - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Output of [[ ]] with string comparison

What is the output of the following bash script snippet?

Bash Scripting

str1="hello"
str2="hello"
if [[ $str1 == $str2 ]]; then
  echo "Match"
else
  echo "No Match"
fi

A Syntax Error

B No Match

C Match

D No output

💡 Hint

The [[ ]] test compares strings for equality.

The [[ $str1 == $str2 ]] condition checks if the two strings are equal. Since both are "hello", it prints "Match".

💻 Command Output

intermediate

Numeric comparison with [[ ]]

What will this script output?

Bash Scripting

num=5
if [[ $num -gt 3 ]]; then
  echo "Greater"
else
  echo "Smaller or equal"
fi

A Syntax Error

B Greater

C Smaller or equal

D No output

💡 Hint

Use -gt for numeric greater than comparison inside [[ ]].

The condition [[ $num -gt 3 ]] checks if num is greater than 3. Since 5 > 3, it prints "Greater".

💻 Command Output

advanced

Testing file existence with [[ ]]

What is the output of this script if the file /etc/passwd exists?

Bash Scripting

if [[ -f /etc/passwd ]]; then
  echo "File exists"
else
  echo "File missing"
fi

A File exists

B File missing

C Syntax Error

D No output

💡 Hint

The -f option tests if a file exists and is a regular file.

The [[ -f /etc/passwd ]] condition checks if the file exists and is a regular file. Usually, /etc/passwd exists, so it prints "File exists".

💻 Command Output

advanced

Logical AND with [[ ]]

What will this script output?

Bash Scripting

a=10
b=20
if [[ $a -lt 15 && $b -gt 15 ]]; then
  echo "Both true"
else
  echo "Condition failed"
fi

A Both true

B Condition failed

C Syntax Error

D No output

💡 Hint

Use && inside [[ ]] for logical AND.

The condition checks if a < 15 and b > 15. Since 10 < 15 and 20 > 15, both are true, so it prints "Both true".

💻 Command Output

expert

Complex string pattern matching with [[ ]]

What is the output of this script?

Bash Scripting

filename="report2024.txt"
if [[ $filename == report[0-9][0-9][0-9][0-9].txt ]]; then
  echo "Pattern matched"
else
  echo "No match"
fi

A Syntax Error

B No match

C No output

D Pattern matched

💡 Hint

The [[ ]] supports pattern matching with glob patterns like [0-9].

The pattern report[0-9][0-9][0-9][0-9].txt matches filenames starting with 'report' followed by exactly 4 digits and '.txt'. The filename matches, so it prints "Pattern matched".