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Text File Operations and Editors

Now that you're comfortable navigating the file system and managing files, it's time to learn how to work with text files—the lifeblood of Linux system administration and development. In this lesson, you'll master essential text manipulation commands and get hands-on with popular text editors.

Learning Goals:

  • Create, view, and manipulate text files using command-line tools
  • Master basic text editors: Nano (beginner-friendly) and Vim (power-user)
  • Search, filter, and transform text content
  • Understand when to use different text editing approaches

Essential Text File Commands​

Creating and Viewing Files​

Let's start with the basics—creating and examining text files.

Creating and viewing files
# Create an empty file
touch example.txt

# Create a file with initial content using echo
echo "Hello, Linux World!" > greeting.txt

# View entire file content
cat greeting.txt

# View with line numbers
cat -n greeting.txt

# View first few lines
head -5 largefile.txt

# View last few lines  
tail -5 logfile.txt

Appending and Combining Files​

Appending and combining content
# Add content to existing file
echo "This is additional text" >> greeting.txt

# Combine multiple files
cat file1.txt file2.txt > combined.txt

# View growing files in real-time (useful for logs)
tail -f /var/log/syslog
tip

Use >> to append content without overwriting existing data. The single > will replace the entire file content!

Text Processing Power Tools​

Searching with grep​

grep is your go-to tool for searching text patterns.

grep examples
# Search for a pattern in a file
grep "error" logfile.txt

# Case-insensitive search
grep -i "warning" system.log

# Search recursively in directories
grep -r "TODO" /home/user/projects/

# Show line numbers with matches
grep -n "function" script.py

# Count occurrences
grep -c "success" results.txt

Stream Editing with sed​

sed allows you to transform text on the fly.

sed examples
# Replace first occurrence per line
sed 's/old/new/' file.txt

# Replace all occurrences
sed 's/old/new/g' file.txt

# Delete lines containing pattern
sed '/pattern/d' file.txt

# Edit file in-place (be careful!)
sed -i 's/foo/bar/g' config.txt

Advanced Text Processing with awk​

awk is a powerful programming language for text processing.

awk examples
# Print specific column
ls -l | awk '{print $9}'

# Print lines where condition is true
awk '$3 > 1000 {print $1}' data.txt

# Custom field separator
awk -F: '{print $1}' /etc/passwd

Text Editors: Nano​

Nano is a simple, beginner-friendly text editor perfect for quick edits.

Basic Nano Usage​

Working with Nano
# Open a file
nano document.txt

# Create new file
nano newfile.txt
note

Nano Keyboard Shortcuts:

  • Ctrl + O - Save file
  • Ctrl + X - Exit
  • Ctrl + K - Cut line
  • Ctrl + U - Paste
  • Ctrl + W - Search
  • Ctrl + \ - Search and replace

The available shortcuts are always displayed at the bottom of the screen!

Text Editors: Vim​

Vim is a powerful modal editor that's worth learning for serious text editing.

Vim Modes and Basics​

Opening Vim
# Open file in Vim
vim config.txt

Vim has different modes:

  • Normal mode: For navigation and commands (default when opening)
  • Insert mode: For typing text
  • Visual mode: For selecting text
  • Command mode: For entering commands
# Essential Vim commands (in Normal mode)
i          # Enter Insert mode
Esc        # Return to Normal mode
:w         # Save file
:q         # Quit
:wq        # Save and quit
:q!        # Quit without saving
dd         # Delete current line
yy         # Copy current line
p          # Paste
u          # Undo
/text      # Search for "text"
warning

Don't panic if you get stuck in Vim! If you can't figure out how to exit, press Esc to ensure you're in Normal mode, then type :q! and press Enter to force quit without saving.

Practical Workflow Examples​

Editing Configuration Files​

Common configuration editing workflow
# Backup original config
sudo cp /etc/ssh/sshd_config /etc/ssh/sshd_config.backup

# Edit the config
sudo nano /etc/ssh/sshd_config

# Or with Vim
sudo vim /etc/ssh/sshd_config

# View changes
diff /etc/ssh/sshd_config.backup /etc/ssh/sshd_config

Log File Analysis​

Analyzing log files
# Find recent errors in system log
grep -i "error" /var/log/syslog | tail -20

# Count unique IP addresses in web log
awk '{print $1}' /var/log/nginx/access.log | sort | uniq -c | sort -nr

# Monitor new log entries in real-time
tail -f /var/log/auth.log | grep "Failed password"

Common Pitfalls​

  • Forgetting Vim modes: New users often get stuck because they don't understand Vim's modal nature. Remember to press Esc to return to Normal mode.

  • Overwriting files with >: Using echo "text" > file.txt will erase the entire file. Use >> to append instead.

  • Editing system files without backup: Always create backups before editing important configuration files.

  • Using wrong line endings: Windows line endings (\r\n) can cause issues in Linux scripts. Use dos2unix to convert if needed.

  • Getting stuck in less/more viewers: When viewing files with less or more, press q to exit.

Summary​

You now have a solid foundation in Linux text file operations! You can:

  • Create, view, and manipulate text files using command-line tools
  • Search and filter content with grep, sed, and awk
  • Edit files confidently using both Nano and Vim
  • Apply these skills to real-world scenarios like log analysis and configuration editing

Remember: Start with Nano for quick edits, but invest time in learning Vim—it will pay off in the long run for serious text editing tasks.

Quiz​

Show quiz

  1. Which command would you use to add "new text" to an existing file without removing its current content?

    • A) echo "new text" > file.txt
    • B) echo "new text" | file.txt
    • C) echo "new text" >> file.txt
    • D) cat "new text" file.txt

  2. You need to search for all occurrences of "ERROR" (case-insensitive) in a log file and see the line numbers. Which grep command should you use?

    • A) grep "ERROR" logfile.txt
    • B) grep -i "error" logfile.txt
    • C) grep -n -i "error" logfile.txt
    • D) grep -r "error" logfile.txt

  3. In Vim, which sequence of commands would you use to save a file and exit?

    • A) Ctrl + S then Ctrl + Q
    • B) :wq then Enter
    • C) :save then :quit
    • D) Esc then :q

  4. What's the main risk of using sed -i 's/old/new/g' important_file.txt without a backup?

    • A) It will create multiple copies of the file
    • B) It might corrupt binary files
    • C) If the command has an error, you could lose your original content
    • D) It will change file permissions

  5. You're viewing a large file with less and want to exit. What do you press?

    • A) Esc
    • B) Ctrl + C
    • C) :q
    • D) q

Answers:

  1. C - The >> operator appends to files without overwriting
  2. C - -n shows line numbers, -i makes search case-insensitive
  3. B - :wq is the Vim command to write (save) and quit
  4. C - sed -i edits files in-place, so errors could permanently alter your file
  5. D - Press q to quit less/more viewers