# System Administration Skill

## System Info
```bash
uname -a                 # Kernel info
cat /etc/os-release      # OS details
hostname                 # Hostname
uptime                  # System uptime
```

## Process Management
```bash
ps aux                  # All processes
top                     # Interactive view
htop                    # Better top
kill -9 pid             # Force kill
pkill process_name      # Kill by name
```

## Memory & Disk
```bash
free -h                 # Memory usage
df -h                   # Disk usage
du -sh folder           # Folder size
```

## Network
```bash
ip addr                 # IP addresses
netstat -tulpn          # Listening ports
ss -tulpn              # Alternative to netstat
curl url               # HTTP request
wget url               # Download
```

## Services
```bash
systemctl status service
systemctl start service
systemctl stop service
systemctl restart service
systemctl enable service
```

## User Management
```bash
whoami                  # Current user
id                       # User info
useradd name            # Add user
usermod -aG group user # Add to group
passwd user             # Change password
```

## Logs
```bash
journalctl -u service   # Service logs
tail -f /var/log/syslog
dmesg | tail
```