ls (list files and directories) in Linux CLI - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of ls -l in a directory with one file named file.txt?

You run the command ls -l in a directory containing a single file named file.txt. What will the output look like?

Linux CLI

ls -l

A

total 0
-rw-r--r-- 1 user user 0 Apr 27 12:00 file.txt

B -rw-r--r-- 1 user user 0 Apr 27 12:00 file.txt

C

total 1
-rw-r--r-- 1 user user 0 Apr 27 12:00 file.txt

D file.txt

💡 Hint

The -l option shows detailed info including permissions, owner, size, and date.

The ls -l command lists files with detailed info. It starts with a line showing total blocks (usually 0 or more), then one line per file with permissions, links, owner, group, size, date, and name.

💻 Command Output

intermediate

What does ls -a show in a directory with files file1, .hidden?

You run ls -a in a directory containing two files: file1 and .hidden. What will the output be?

Linux CLI

ls -a

A file1

B file1 .hidden

C .hidden

D . .. file1 .hidden

💡 Hint

The -a option shows all files, including hidden and special entries.

The ls -a command lists all files including hidden files (those starting with a dot) and the special entries . (current directory) and .. (parent directory).

📝 Syntax

advanced

Which ls command lists files sorted by modification time, newest first?

You want to list files sorted by modification time, newest first. Which command is correct?

A ls -ltr

B ls -lt

C ls -ltu

D ls -lS

💡 Hint

The -t option sorts by modification time, -r reverses order.

ls -lt lists files in long format sorted by modification time, newest first. Adding -r reverses order (oldest first). -lS sorts by size, -ltu sorts by access time.

🔧 Debug

advanced

Why does ls -l /nonexistent produce an error?

You run ls -l /nonexistent but get an error message. What is the reason?

A The -l option is invalid with absolute paths

B You need root permissions to list /nonexistent

C The directory /nonexistent does not exist

D The command requires a trailing slash on directories

💡 Hint

Check if the directory exists before listing.

The error occurs because the directory /nonexistent does not exist. ls cannot list files in a directory that is missing.

🚀 Application

expert

How to list only directories in current folder using ls and shell features?

You want to list only directories (not files) in the current folder using ls combined with shell commands. Which command achieves this?

A ls -d */

B ls -l | grep '^d'

C ls -a | grep -v '^-'

D ls -F | grep '/'

💡 Hint

The -d option lists directories themselves, and */ matches directories.

ls -d */ lists only directories in the current folder by matching names ending with a slash. Other options may list files or rely on parsing output which can be unreliable.