find command basics in Linux CLI - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Find files by name

What is the output of this command if the current directory contains files: report.txt, data.csv, and notes.txt?

Linux CLI

find . -name '*.txt'

A Syntax error

B ./data.csv

C

report.txt
notes.txt

D

./report.txt
./notes.txt

💡 Hint

The -name option filters files by pattern, including the path.

The find command searches recursively from the current directory (.) and lists files matching '*.txt'. It shows relative paths starting with './'.

💻 Command Output

intermediate

Find files by size

What files will this command list if the directory has files: a.log (500 bytes), b.log (1500 bytes), and c.log (2500 bytes)?

Linux CLI

find . -size +1000c

A No output

B

./a.log
./b.log
./c.log

C

./b.log
./c.log

D ./a.log

💡 Hint

The -size +1000c finds files larger than 1000 bytes.

Files larger than 1000 bytes are b.log and c.log. The command lists them with relative paths.

📝 Syntax

advanced

Correct find syntax for multiple conditions

Which option correctly finds files with extension .txt or .md in the current directory?

A find . -name '*.txt' -o -name '*.md'

B find . -name '*.txt' -and -name '*.md'

C find . -name '*.txt' -or -name '*.md'

D find . -name '*.txt' || -name '*.md'

💡 Hint

Use the correct logical OR operator for find.

The -o option means OR in find. -or is not valid syntax. -and means AND, and || is shell syntax, not find syntax.

🔧 Debug

advanced

Why does this find command fail?

This command is intended to find all files modified in the last 7 days but returns no results. Why? find . -mtime 7

A It should use -mmin instead of -mtime

B It finds files modified exactly 7 days ago, not within 7 days

C The command syntax is invalid

D It only finds directories, not files

💡 Hint

Check what the number after -mtime means.

The -mtime 7 finds files modified exactly 7*24 hours ago, not within the last 7 days. To find files modified within 7 days, use -mtime -7.

🚀 Application

expert

Find and delete empty files safely

Which command safely finds and deletes all empty files in the current directory and its subdirectories?

A find . -type f -empty -delete

B find . -empty -exec rm {} \;

C find . -type f -size 0 -exec rm -f {} \;

D find . -type f -size 0 -delete

💡 Hint

Use the safest and simplest way to delete empty files with find.

Option A uses -empty to find empty files and -delete to remove them safely. Option A tries to delete empty directories too. Option A deletes files by size but is less clear. Option A deletes files by size but -delete is safer combined with -empty.

Practice

1. What does the find command do in Linux?

easy

A. Copies files from one folder to another

B. Deletes files permanently

C. Searches for files and directories based on criteria

D. Displays the contents of a file

Solution

1. Step 1: Understand the purpose of the find command

   The find command is used to locate files and directories by searching through folders and subfolders.

2. Step 2: Compare options

   Options B, C, and D describe other commands like rm, cp, and cat, not find.

3. Final Answer:

   Searches for files and directories based on criteria -> Option C

4. Quick Check:

   find = search files [OK]

Hint: Remember: find means locate files/folders fast [OK]

Common Mistakes:

• Confusing find with delete or copy commands
• Thinking find edits files
• Assuming find shows file contents

2. Which of the following is the correct syntax to find all files named notes.txt in the current directory and its subdirectories?

easy

A. find . -name notes.txt

B. find -name notes.txt .

C. find notes.txt -name .

D. find . notes.txt -name

Solution

1. Step 1: Recall find command syntax

   The correct syntax is: find [path] [options]. Here, '.' means current directory, '-name' specifies the filename.

2. Step 2: Check each option

   find . -name notes.txt matches the correct syntax. Options A, B, and D have misplaced arguments or options.

3. Final Answer:

   find . -name notes.txt -> Option A

4. Quick Check:

   find . -name filename [OK]

Hint: Path first, then options like -name [OK]

Common Mistakes:

• Putting filename before path
• Missing dot for current directory
• Wrong order of options and arguments

3. What will be the output of the command find /tmp -type d -name "test" if there is a directory named test inside /tmp?

medium

A. It will list the full path of the directory named test inside /tmp

B. It will list all files named test inside /tmp

C. It will delete the directory named test inside /tmp

D. It will show an error because of incorrect syntax

Solution

1. Step 1: Understand the command options

   /tmp is the search path, -type d means only directories, -name "test" looks for name 'test'.

2. Step 2: Predict output

   The command will print the full path of any directory named 'test' inside /tmp and its subfolders.

3. Final Answer:

   It will list the full path of the directory named test inside /tmp -> Option A

4. Quick Check:

   find with -type d lists directories [OK]

Hint: -type d means directories only [OK]

Common Mistakes:

• Confusing -type d with files
• Expecting deletion instead of listing
• Assuming syntax error without checking

4. You run find /home/user -name '*.txt' but get no results even though there are .txt files. What is the most likely problem?

medium

A. The quotes prevent the shell from expanding the wildcard

B. The path /home/user does not exist

C. The command should use -type d instead of -name

D. The wildcard * is not supported by find

Solution

1. Step 1: Understand wildcard usage in find

   Using quotes around '*.txt' prevents the shell from expanding the wildcard, which is correct because find handles the pattern matching itself.

2. Step 2: Identify common mistake

   With correct syntax, no results despite .txt files existing suggests the path /home/user does not exist or is inaccessible.

3. Final Answer:

   The path /home/user does not exist -> Option B

4. Quick Check:

   ls /home/user [OK]

Hint: Verify path exists before searching [OK]

Common Mistakes:

• Removing quotes and letting shell expand
• Using -type d for files
• Wrong path assumption

5. How can you use the find command to locate all files larger than 1MB in the /var/log directory and delete them safely after confirmation?

hard

A. find /var/log -type d -size +1M -ok rm {} \;

B. find /var/log -type f -size +1M -delete

C. find /var/log -size 1M -exec rm {} \;

D. find /var/log -type f -size +1M -ok rm {} \;

Solution

1. Step 1: Identify criteria for files larger than 1MB

   -type f means files, -size +1M means size greater than 1 megabyte.

2. Step 2: Choose safe deletion method

   -ok rm {} \; asks for confirmation before deleting each file, which is safer than -delete or -exec rm without confirmation.

3. Step 3: Check options

   find /var/log -type f -size +1M -ok rm {} \; uses -ok for confirmation, correct. find /var/log -type f -size +1M -delete deletes without confirmation. find /var/log -size 1M -exec rm {} \; uses wrong size syntax and no confirmation. find /var/log -type d -size +1M -ok rm {} \; searches directories, not files.

4. Final Answer:

   find /var/log -type f -size +1M -ok rm {} \; -> Option D

5. Quick Check:

   -ok asks confirmation before delete [OK]

Hint: Use -ok for safe delete with confirmation [OK]

Common Mistakes:

• Using -delete without confirmation
• Wrong size syntax
• Searching directories instead of files