Linux Exercise 4 - Finding Files and Sorting Data

🧪 Linux File-Finding and Data-Sorting Exercise

🔍 Task 1: Find All Files in /home Without Errors

Run:

find /home -type f -print 2>/dev/null

Protocol Notes:

• What does 2>/dev/null do?
• Why might errors occur without it?
• How many files were found?

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📦 Task 2: Find Large Files on the System

Run:

sudo find / -type f -size +1M -print 2>/dev/null

Protocol Notes:

• What does +1M mean?
• Why might sudo be necessary?
• What types of files are typically large?

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🧠 Task 3: Identify File Types in /home (Two Methods)

Method A: Using find and file together

ind /home -type f -exec file '{}' \; 2>/dev/null

Method B: Using a loop

for f in $(find /home -type f 2>/dev/null); do file "$f"; done

Protocol Notes:

• What does the file command do?
• Compare the two methods: which is faster or more readable?
• What kinds of file types did you discover?

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🧭 Task 4: Locate Executables

Try the following:

which bash
type bash
command -v bash

Protocol Notes:

• What are the differences between these commands?
• Which one is POSIX-compliant?
• What does the output tell you?

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⚡ Task 5: Use locate and Refresh the Index

1. Run:

   locate ".txt"

2. Then refresh the index:

   sudo updatedb

3. Run locate again and compare results.

Protocol Notes:

• How fast is locate compared to find?
• Did the results change after updating the index?
• What are the limitations of locate?

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🧪 Task 6: Additional Use-Cases

• Use grep -rl "TODO" ~/ to find files containing the word “TODO”.
• Try whereis bash and interpret the output.
• If installed, try fd .txt and compare it to find.

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📁 Task 7: Create Sample Data for Sorting

1. Create a file called numbers.txt with the following content (in random order):

   42
   7
   19
   7
   3
   42
   100

2. Sort the file numerically:

   sort -n numbers.txt

3. Sort the file in reverse numeric order:

   sort -nr numbers.txt

Protocol Notes:

• What does -n do?
• What does -r do?
• How does the output change?

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🧮 Task 8: Count Duplicate Entries

Run:

sort numbers.txt | uniq -c

Protocol Notes:

• What does the output mean?
• Why is sort necessary before uniq -c?
• What happens if you run uniq -c without sorting?

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📑 Task 9: Filter Unique and Duplicate Lines

Try:

sort numbers.txt | uniq -u
sort numbers.txt | uniq -d

Protocol Notes:

• What’s the difference between -u and -d?
• What lines are considered duplicates?
• How does sorting affect the result?

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📋 Task 10: Sort by Column in a CSV File

1. Create a file called students.csv with the following content:

   Alice,85
   Bob,92
   Charlie,78
   Dana,85
   Eve,92

2. Sort by score (second column):

   sort -t, -k2 students.csv

3. Sort by name (first column):

   sort -t, -k1 students.csv

Protocol Notes:

• What does -t, do?
• What does -k2 mean?
• How does changing the column affect the sort order?

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📈 Task 11: Sort and Rank Names by Frequency

1. Create a file names.txt with repeated names:

   Alice
   Bob
   Alice
   Charlie
   Bob
   Bob
   Dana

2. Run:

   sort names.txt | uniq -c | sort -nr

Protocol Notes:

• What does each part of the pipeline do?
• What does the final output represent?
• How could this be used in real-world scenarios?

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📑 Protocol (What to Hand In)

Each student must create a protocol (log) containing:

• Command executed
• Output received (full or partial if very long)
• Explanation (1–2 sentences) of what the command did
• Observation/interpretation of what they learned

Example:

Command: file sample.zip
Output: sample.zip: Zip archive data, at least v2.0 to extract
Explanation: Identified sample.zip as a compressed archive file.
Observation: Shows that zip files are binary and need archive tools to inspect contents.

Command: sudo tail -f /var/log/syslog
Output: (live log output appears)
Explanation: Monitors new log entries in real-time.
Observation: Useful for watching system activity as it happens.