File existence checks in Bash Scripting - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Check if a file exists and print a message

What is the output of this script if the file example.txt exists in the current directory?

Bash Scripting

if [ -f example.txt ]; then
  echo "File exists"
else
  echo "File does not exist"
fi

A File does not exist

B File exists

C Syntax error

D No output

💡 Hint

The -f test checks if a regular file exists.

The [ -f filename ] condition returns true if the file exists and is a regular file. Since example.txt exists, it prints "File exists".

💻 Command Output

intermediate

Check if a directory exists

What will this script output if the directory myfolder does NOT exist?

Bash Scripting

if [ -d myfolder ]; then
  echo "Directory found"
else
  echo "Directory missing"
fi

A Syntax error

B Directory found

C No output

D Directory missing

💡 Hint

The -d test checks for directories.

The [ -d myfolder ] condition is false if the directory does not exist, so it prints "Directory missing".

📝 Syntax

advanced

Identify the syntax error in file existence check

Which option contains a syntax error when checking if data.log exists as a file?

A if test -f data.log; then echo "Exists"; fi

B if [[ -f data.log ]]; then echo "Exists"; fi

C if [ -f data.log ] then echo "Exists"; fi

D if [ -f data.log ]; then echo "Exists"; fi

💡 Hint

Check for missing semicolons or line breaks before then.

Option C is missing a semicolon or newline before then, causing a syntax error.

🚀 Application

advanced

Script to check multiple files and report missing ones

Given the script below, what will be the output if file1.txt exists but file2.txt does not?

Bash Scripting

for file in file1.txt file2.txt; do
  if [ ! -f "$file" ]; then
    echo "$file is missing"
  fi
done

A file2.txt is missing

B

file1.txt is missing
file2.txt is missing

C file1.txt is missing

D No output

💡 Hint

The script prints only files that do NOT exist.

Since file1.txt exists, it is skipped. file2.txt does not exist, so it prints "file2.txt is missing".

🧠 Conceptual

expert

Understanding file existence test with symbolic links

Consider a symbolic link link.txt pointing to a regular file. Which test returns true if you want to check if link.txt exists regardless of target?

A [ -e link.txt ]

B [ -f link.txt ]

C [ -L link.txt ]

D [ -d link.txt ]

💡 Hint

-e checks if the file or link exists, -L checks if it is a link.

The -e test returns true if the file or symbolic link exists, regardless of the target's existence. -f checks if the target is a regular file, -L checks if it is a symbolic link, and -d checks for directories.