Linux Server Administration Guide
Linux server administration encompasses the essential skills needed to manage, maintain, and troubleshoot Linux-based servers. Whether you are running a VPS or a dedicated server, mastering these fundamentals is critical.
Essential Commands
File System Navigation
ls -la # list files with details and hidden files cd /var/www # change directory pwd # print working directory du -sh /var/* # disk usage summary df -h # filesystem disk space
File Operations
cp -r source/ dest/ # copy recursively mv oldname newname # move or rename rm -rf directory/ # remove directory (use with caution) chmod 755 script.sh # set permissions chown user:group file # change ownership
Text Processing
cat /var/log/syslog # view file contents tail -f /var/log/nginx/access.log # follow log in real time grep "error" /var/log/syslog # search for patterns nano /etc/nginx/nginx.conf # edit files
User Management
Creating Users
sudo adduser newuser # create user interactively sudo usermod -aG sudo newuser # add to sudo group sudo passwd newuser # set or change password
Managing Permissions
Linux permissions follow the owner-group-others model:
- r (4) — read
- w (2) — write
- x (1) — execute
- Server Security Best Practices
- Basic Server Administration Skills for Beginners
- First Steps with Your New Dedicated Server
Example: chmod 750 file gives owner full access, group read+execute, others nothing.
Service Management with systemd
Modern Linux distributions use systemd to manage services:
sudo systemctl start nginx # start a service sudo systemctl stop nginx # stop a service sudo systemctl restart nginx # restart a service sudo systemctl enable nginx # start on boot sudo systemctl disable nginx # don't start on boot sudo systemctl status nginx # check service status journalctl -u nginx -f # view service logs
Creating a Custom Service
Create /etc/systemd/system/myapp.service:
[Unit] Description=My Application After=network.target
[Service] User=appuser WorkingDirectory=/opt/myapp ExecStart=/opt/myapp/start.sh Restart=always
[Install] WantedBy=multi-user.target
Then:
sudo systemctl daemon-reload sudo systemctl enable --now myapp
Package Management
| Task !! Debian/Ubuntu !! CentOS/RHEL |
|---|
| Update package list || apt update || dnf check-update |
| Upgrade packages || apt upgrade || dnf upgrade |
| Install package || apt install nginx || dnf install nginx |
| Remove package || apt remove nginx || dnf remove nginx |
| Search packages || apt search keyword || dnf search keyword |
Process Management
ps aux # list all processes top / htop # interactive process viewer kill PID # terminate a process kill -9 PID # force kill nice -n 10 command # run with lower priority
Networking
ip addr show # show network interfaces ss -tulnp # show listening ports curl -I https://example.com # check HTTP headers ping -c 4 8.8.8.8 # test connectivity traceroute example.com # trace network path