Lab: Automation Scripts

7.5. Lab: Automation Scripts#

Apply control flow to build practical, real-world automation scripts.

7.5.1. Exercise 6: System Monitor#

Create a script sysmonitor.sh that:

  • Shows current date/time

  • Shows disk usage for /

  • Shows top 3 memory-hungry processes

  • Shows network interfaces and IP addresses

  • Runs continuously (optional: add refresh interval)

Example:

$ bash sysmonitor.sh
=== System Monitor ===
Date: Thu Jan 1 12:00:00 UTC 2024
Disk Usage: 45%
Top Memory Users:
  1. systemd (256MB)
  2. bash (128MB)
  3. sshd (64MB)
Network: 192.168.1.100 (eth0)

Hints:

  • Use date for time

  • Use df for disk usage

  • Use ps for processes

  • Use ip addr for network info

  • Optional: use while true with sleep for refresh

7.5.2. Exercise 5: Log Analyzer#

Create a script analyze_logs.sh that:

  • Takes a log file as argument

  • Counts error, warning, and info lines

  • Shows lines containing “ERROR”

  • Skips comment lines (starting with #)

  • Shows summary statistics

Example:

$ bash analyze_logs.sh app.log
=== Log Analysis ===
Total lines: 100
Errors: 5
Warnings: 12
Info: 83

Error lines:
[Error 1]
[Error 2]
...

Hints:

  • Use while read to read file line by line

  • Use continue to skip comments and empty lines

  • Use grep or [[ ]] to check for keywords

  • Count occurrences in variables

7.5.3. Exercise 4: Backup Script#

Create a script backup.sh that:

  • Takes a source directory and destination

  • Validates both paths exist

  • Creates backup with timestamp

  • Shows progress while copying files

  • Reports final status

Example:

$ bash backup.sh /home/user/docs /backup
Validating paths...
Source: /home/user/docs ✓
Target: /backup ✓
Backing up: file1.txt
Backing up: file2.txt
Backed up 2 files
Backup complete: /backup/docs.backup.20240101_120000

Hints:

  • Use arguments $1 and $2

  • Use -d to check if directory exists

  • Use timestamp: date +%Y%m%d_%H%M%S

  • Use for loop to process files

  • Echo progress messages

7.5.4. Exercise 3: User Input Validator#

Create a script register.sh that:

  • Asks for username (3+ characters)

  • Asks for email (must contain @)

  • Asks for age (must be number >= 18)

  • Validates each input

  • Shows success or error messages

Example:

$ bash register.sh
Enter username (3+ chars): ab
Invalid: too short
Enter username (3+ chars): alice
Enter email: alice@example.com
Enter age: 20
Registration successful!

Hints:

  • Use read -p for prompts

  • Use [[ ]] for string/pattern matching

  • Use =~ for regex patterns

  • Loop if validation fails

7.5.5. Exercise 2: File Processor#

Create a script process_files.sh that:

  • Takes a directory as argument

  • Processes each .txt file in that directory

  • Shows filename and line count

  • Counts total lines across all files

Example:

$ bash process_files.sh /tmp
Processing file1.txt: 42 lines
Processing file2.txt: 18 lines
Total across 2 files: 60 lines

Hints:

  • Use for loop with glob pattern

  • Use wc -l to count lines

  • Use variable to accumulate totals

  • Check if directory exists first

7.5.6. Exercise 1: Menu System#

Create a script menu.sh that:

  • Displays a menu of options

  • Uses a loop to allow multiple selections

  • Uses case to handle selections

  • Allows user to exit

Example:

=== System Menu ===
1. Show date
2. Show disk usage
3. Show users
4. Exit

Enter choice: 1
[current date displayed]

Enter choice: 4
Goodbye!

Hints:

  • Use while true for infinite loop

  • Use read to get user input

  • Use case for menu selection

  • Use break to exit loop

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