Lab 11: nano — Text Editing

Objective

Edit files with nano: open, navigate, write, save, search, and use keyboard shortcuts. nano is the easiest terminal editor to learn — ideal for quick config file edits on servers.

Time: 25 minutes | Level: Foundations | Docker: docker run -it --rm ubuntu:22.04 bash

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Step 1: Install and Verify

apt-get update -qq && apt-get install -y -qq nano
nano --version | head -1

📸 Verified Output:

 GNU nano, version 6.2

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Step 2: nano Interface Overview

When you open nano, the screen shows:

  GNU nano 6.2            filename.txt              Modified
  ─────────────────────────────────────────────────────────
  (your file content here)


  ─────────────────────────────────────────────────────────
  ^G Help    ^O Write   ^W Where   ^K Cut     ^X Exit
  ^F Find    ^R Replace ^T Execute ^U Paste   ^J Justify

💡 The ^ symbol means Ctrl. So ^X = Ctrl+X (exit). The shortcuts are always visible at the bottom — you never need to memorise them.

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Step 3: Create and Edit a File

# Create a config file for a fictional app
cat > /tmp/myapp.conf << 'EOF'
# MyApp Configuration
HOST=localhost
PORT=8080
DEBUG=false
LOG_LEVEL=INFO
DB_NAME=myapp_db
EOF

cat /tmp/myapp.conf

📸 Verified Output:

# MyApp Configuration
HOST=localhost
PORT=8080
DEBUG=false
LOG_LEVEL=INFO
DB_NAME=myapp_db

To edit this in nano:

nano /tmp/myapp.conf

Essential nano shortcuts:

Key	Action
Ctrl+O then Enter	Save (Write Out)
Ctrl+X	Exit
Ctrl+W	Search (Where is)
Ctrl+K	Cut entire line
Ctrl+U	Paste (Un-cut)
Ctrl+G	Help
Ctrl+/	Go to line number
Alt+U	Undo
Alt+E	Redo
Arrow keys	Navigate
Ctrl+C	Show cursor position

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Step 4: nano Command-Line Options

# Open with line numbers visible
nano -l /tmp/myapp.conf

# Open at a specific line number
nano +3 /tmp/myapp.conf

# Read-only mode (view without accidental edits)
nano -v /tmp/myapp.conf

# No line wrap (useful for config files and code)
nano -w /tmp/myapp.conf

💡 nano -w is important for editing config files where line wrapping would corrupt the syntax. Always use -w when editing /etc/nginx/nginx.conf, /etc/ssh/sshd_config, etc.

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Step 5: Creating a Shell Script with nano

# Create script via heredoc (simulates typing in nano)
cat > /tmp/backup.sh << 'SCRIPT'
#!/bin/bash
# Simple backup script
# Edit this with: nano backup.sh

BACKUP_DIR="/tmp/backups"
SOURCE_DIR="/etc"
DATE=$(date +%Y%m%d_%H%M%S)

mkdir -p "$BACKUP_DIR"
tar -czf "$BACKUP_DIR/etc_backup_${DATE}.tar.gz" "$SOURCE_DIR" 2>/dev/null
echo "Backup created: etc_backup_${DATE}.tar.gz"
SCRIPT

chmod +x /tmp/backup.sh
/tmp/backup.sh
ls -lh /tmp/backups/

📸 Verified Output:

Backup created: etc_backup_20260305_005800.tar.gz
total 16K
-rw-r--r-- 1 root root 14K Mar  5 00:58 etc_backup_20260305_005800.tar.gz

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Step 6: Search and Replace in nano

Within nano, to search and replace:

1. Press Ctrl+\ (on some systems Alt+R)

2. Type search string → Enter

3. Type replacement string → Enter

4. Press A to replace all, or Y/N for each

To navigate to a specific line:

1. Press Ctrl+/

2. Type line number → Enter

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Step 7: nano for System Configuration

# View /etc/ssh/sshd_config key settings
grep -v '^#' /etc/ssh/sshd_config 2>/dev/null | grep -v '^$' | head -10 \
  || echo "sshd_config not available in container"

# nano is the standard editor for quick sysadmin tasks:
echo "Common uses of nano:"
echo "  nano /etc/hosts         — add local DNS entries"
echo "  nano /etc/crontab       — schedule jobs"
echo "  nano /etc/ssh/sshd_config  — harden SSH"
echo "  nano /etc/fstab         — mount points"
echo "  nano ~/.bashrc          — shell customisation"

📸 Verified Output:

sshd_config not available in container
Common uses of nano:
  nano /etc/hosts         — add local DNS entries
  nano /etc/crontab       — schedule jobs
  nano /etc/ssh/sshd_config  — harden SSH
  nano /etc/fstab         — mount points
  nano ~/.bashrc          — shell customisation

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Step 8: Capstone — Edit a Simulated NGINX Config

cat > /tmp/nginx_site.conf << 'EOF'
server {
    listen 80;
    server_name example.com;
    root /var/www/html;
    index index.html;

    location / {
        try_files $uri $uri/ =404;
    }

    location /api {
        proxy_pass http://127.0.0.1:3000;
        proxy_set_header Host $host;
    }

    # Security headers
    add_header X-Frame-Options "SAMEORIGIN";
    add_header X-Content-Type-Options "nosniff";
}
EOF

echo "Config file created:"
cat -n /tmp/nginx_site.conf
echo ""
echo "File stats:"
wc -l /tmp/nginx_site.conf
echo "lines in nginx config"

📸 Verified Output:

Config file created:
     1	server {
     2	    listen 80;
     3	    server_name example.com;
     4	    root /var/www/html;
     5	    index index.html;
     6	
     7	    location / {
     8	        try_files $uri $uri/ =404;
     9	    }
    10	
    11	    location /api {
    12	        proxy_pass http://127.0.0.1:3000;
    13	        proxy_set_header Host $host;
    14	    }
    15	
    16	    # Security headers
    17	    add_header X-Frame-Options "SAMEORIGIN";
    18	    add_header X-Content-Type-Options "nosniff";
    19	}

File stats:
19 /tmp/nginx_site.conf
lines in nginx config

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Summary

Shortcut	Action
Ctrl+O	Save file
Ctrl+X	Exit
Ctrl+W	Search
Ctrl+\	Search and replace
Ctrl+K	Cut line
Ctrl+U	Paste
Ctrl+/	Go to line number
Alt+U	Undo
nano -l	Show line numbers
nano -w	No line wrap