Every system administrator should master these baseline skills:

• CLI Proficiency: Bash/PowerShell scripting examples:

  # Bash disk monitoring script
  #!/bin/bash
  THRESHOLD=90
  CURRENT=$(df / | grep / | awk '{ print $5}' | sed 's/%//g')
  if [ "$CURRENT" -gt "$THRESHOLD" ]; then
      echo "Warning: Disk usage at $CURRENT%" | mail -s "Disk Alert" admin@example.com
  fi

• Version Control: Basic Git for configuration management:

  # Typical workflow for config changes
  git clone ssh://admin@git.example.com/config-repo.git
  cd config-repo
  nano network.conf
  git commit -am "Updated DNS settings"
  git push origin master

• Infrastructure as Code: Simple Ansible playbook example:

  ---
  - hosts: webservers
    become: yes
    tasks:
      - name: Ensure Apache is installed
        apt:
          name: apache2
          state: present
      - name: Copy custom config
        copy:
          src: /srv/httpd.conf
          dest: /etc/httpd/conf/httpd.conf
          owner: root
          group: root
          mode: '0644'

router# configure terminal
router(config)# interface GigabitEthernet0/1
router(config-if)# description "Server VLAN"
router(config-if)# switchport mode access
router(config-if)# switchport access vlan 10

# Create LVM volume
pvcreate /dev/sdb1
vgcreate storage_vg /dev/sdb1
lvcreate -L 500G -n data_lv storage_vg
mkfs.ext4 /dev/storage_vg/data_lv

-- PostgreSQL maintenance
VACUUM ANALYZE;
CREATE USER app_user WITH PASSWORD 'secure123';
GRANT SELECT ON ALL TABLES IN SCHEMA public TO app_user;

Essential for contemporary environments:

• Container Orchestration: Docker/Kubernetes basics

  # Simple Docker-compose for services
  version: '3'
  services:
    web:
      image: nginx:alpine
      ports:
        - "80:80"
      volumes:
        - ./config:/etc/nginx/conf.d

• Cloud Platforms: AWS/Azure fundamentals

  # AWS CLI EC2 example
  aws ec2 run-instances \
      --image-id ami-0abcdef1234567890 \
      --count 1 \
      --instance-type t2.micro \
      --key-name MyKeyPair \
      --security-group-ids sg-903004f8 \
      --subnet-id subnet-6e7f829e

Critical tools and techniques:

• Nagios/Icinga configuration

  define service {
      host_name               web-server
      service_description     HTTP
      check_command           check_http
      max_check_attempts      3
      normal_check_interval   5
      retry_check_interval    1
      contact_groups          admins
  }

• Log analysis with ELK stack

  # Sample logstash filter for Apache logs
  filter {
    grok {
      match => { "message" => "%{COMBINEDAPACHELOG}" }
    }
    date {
      match => [ "timestamp" , "dd/MMM/yyyy:HH:mm:ss Z" ]
    }
  }

Non-negotiable security fundamentals:

• SSH hardening example

  # /etc/ssh/sshd_config
  Port 2222
  PermitRootLogin no
  PasswordAuthentication no
  X11Forwarding no
  MaxAuthTries 3
  ClientAliveInterval 300
  ClientAliveCountMax 0

• Firewall rules with iptables

  # Basic web server rules
  iptables -A INPUT -p tcp --dport 80 -j ACCEPT
  iptables -A INPUT -p tcp --dport 443 -j ACCEPT
  iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
  iptables -P INPUT DROP

Every sysadmin should master these fundamental technical areas:

• Operating Systems: Deep understanding of Linux/Windows server environments

  # Example Linux command for checking disk space
  df -h

• Networking: TCP/IP, DNS, DHCP, firewalls, and routing

  # Basic network troubleshooting
  ping example.com
  traceroute example.com
  netstat -tuln

• Scripting: Bash, PowerShell, or Python for automation

  # Simple bash script to monitor disk usage
  #!/bin/bash
  THRESHOLD=90
  CURRENT=$(df / | grep / | awk '{print $5}' | sed 's/%//g')
  if [ "$CURRENT" -gt "$THRESHOLD" ]; then
      echo "Warning: Disk space low - $CURRENT% used"
  fi

While core skills overlap, different admin roles require specific expertise:

Network Administrators

• Advanced routing protocols (BGP, OSPF)
• Network security (IDS/IPS, VPNs)
• Switch and router configuration

Storage Administrators

# LVM commands example
pvcreate /dev/sdb1
vgcreate vg_data /dev/sdb1
lvcreate -L 100G -n lv_archive vg_data

Database Administrators

-- Basic MySQL maintenance
OPTIMIZE TABLE important_table;
ANALYZE TABLE user_data;
SHOW PROCESSLIST;

Build experience through:

• Home lab with virtualization (Proxmox, ESXi)
• Cloud platforms (AWS, Azure)
• Configuration management (Ansible, Puppet)

# Sample Ansible playbook for web server setup
- hosts: webservers
  become: yes
  tasks:
    - name: Install Apache
      apt:
        name: apache2
        state: present

Successful sysadmins also need:

• Documentation practices
• Incident response procedures
• Communication with non-technical stakeholders