System Administration Skills

This tutorial covers the fundamental skills needed to get started in system administration. Learn about operating systems, user management, networking basics, system monitoring, and automation using shell scripts. Real-world examples and practice exercises are provided.

Beginner30 minutes

Step 1: Operating System Fundamentals

- Understand the role of an operating system

- Compare Linux, macOS and Windows for system administration

- Learn basic OS commands and navigation

- Practice with the command line interface

ls -l /etc

Practice Exercise

Write commands to:

Create a new directory called scripts in your home directory
Create a new empty file in scripts called sys_info.sh
Change the file permissions of sys_info.sh to be executable

Show Solution

1. mkdir ~/scripts
2. touch ~/scripts/sys_info.sh
3. chmod +x ~/scripts/sys_info.sh

Step 2: User and Group Management

- Create, modify and delete user accounts

- Understand Linux file permissions and ownership

- Manage groups and group membership

- Set and modify file permissions

useradd -m john

Practice Exercise

Write commands to:

Create a new user account named mike with default settings
Add mike to the existing group developers
Copy your scripts directory to mike's home directory
Change ownership of mike's scripts directory to mike

Show Solution

1. sudo useradd -m mike
2. sudo usermod -a -G developers mike 
3. sudo cp -r ~/scripts /home/mike
4. sudo chown -R mike:mike /home/mike/scripts

Step 3: Networking Basics

- Understand IP addresses, subnets, and ports

- Configure network interfaces

- Diagnose network connectivity issues

- Learn key networking commands

ip addr show

Practice Exercise

Write commands to:

Display your system's hostname
Show IP address and subnet mask of your ethernet interface
Ping google.com and show first 4 responses
Trace the route packets take to reach www.linkedin.com

Show Solution

1. hostname
2. ip addr show eth0
3. ping -c 4 google.com
4. traceroute www.linkedin.com

Step 4: System Monitoring Essentials

- Monitor CPU, memory and disk usage

- Check system logs for errors

- Set up basic performance monitoring

- Learn to use tools like top, df, and tail

top -c

Practice Exercise

Write commands to:

Display top 5 processes consuming the most memory
Show current disk usage of your home directory
Monitor system logs in real-time for error messages
Save error messages from system logs to a file called errors.log in your scripts directory

Show Solution

1. ps aux --sort=-%mem | head -n 6
2. du -sh ~
3. sudo tail -f /var/log/syslog | grep --color -i error
4. sudo grep -i error /var/log/syslog > ~/scripts/errors.log

Step 5: Automation with Shell Scripts

- Understand basic shell script syntax

- Learn concepts like variables, conditions, and loops

- Automate repetitive tasks with simple scripts

- Schedule scripts with cron

#!/bin/bash
echo "Hello, $USER"

Practice Exercise

Write a shell script to:

Print "System Info Report" followed by the current date and time
Save the output of the top command to a file called top_output.txt in the current directory
Append the disk usage of the / directory to the same file on the next line
Print "Report generated!" when done

Bonus: Schedule the script to run daily at 8am using crontab

Show Solution

#!/bin/bash
echo "System Info Report"
date
top -n 1 -b > top_output.txt
du -sh / >> top_output.txt
echo "Report generated!"
```

To schedule in crontab:
`0 8 * * * /path/to/script.sh`