Linux questions and answers

Use this page as a quick reference for common Ubuntu self-hosting tasks.

Run a script as a service

If you run a script like ./myscript.sh and want it to start automatically after reboot, create a systemd unit.

/etc/systemd/system/myscript.service

[Unit]
Description=Virtual Distributed Ethernet
After=network.target

[Service]
Type=simple
ExecStart=/usr/bin/YOUR_SCRIPT
Restart=on-failure

[Install]
WantedBy=multi-user.target

Reload systemd, enable the service, and start it:

Reload and enable service

sudo systemctl daemon-reload
sudo systemctl enable myscript.service
sudo systemctl start myscript.service
sudo systemctl status myscript.service

Schedule a nightly reboot

Open your crontab:

crontab -e

Add this line at the bottom:

0 4 * * * /sbin/shutdown -r +5

This announces reboot at 04:00 and reboots at 04:05.

Cron format:

m h dom mon dow command

Note

Run sudo crontab -e if your reboot command needs root-level execution.

Remove old or unused Docker data

Check Docker disk usage:

docker system df

Prune commands:

• docker container prune
• docker image prune
• docker network prune
• docker volume prune
• docker system prune

Remove all unused images (not only dangling):

docker image prune -a

Remove most unused Docker objects:

docker system prune --all

Caution

-a and --all can remove images you still want to keep for fast redeploys.

Clean your server

Check filesystem usage:

df -h

Install and run ncdu for interactive analysis:

Install ncdu

sudo apt install -y ncdu

Scan root filesystem

sudo ncdu /

Caution

Be careful with manual file deletion in system directories.

Common cleanup targets:

1. Old logs in /var/log:

   sudo journalctl --vacuum-time=2d

2. Unused Docker objects in /var/lib/docker:

   sudo docker image prune
   sudo docker container prune
   sudo docker network prune
   sudo docker volume prune
   sudo docker system prune -a

3. Unused packages:

   sudo apt autoremove

Note

For Pterodactyl hosts, avoid manual backup deletion in /var/lib/pterodactyl because panel state can become inconsistent.

Scripts

Geo check

wget -qO - "https://raw.githubusercontent.com/vernette/ipregion/refs/heads/master/ipregion.sh" | bash

Speedtest

sudo apt update && sudo apt install -y curl && curl -s https://packagecloud.io/install/repositories/ookla/speedtest-cli/script.deb.sh | sudo bash && sudo apt install -y speedtest && speedtest

IP check for service blocks

bash <(curl -Ls IP.Check.Place) -l en

Environment info and tests with Russian ISPs

wget -qO- speedtest.artydev.ru | bash

Environment info and tests with ISPs

wget -qO- bench.sh | bash

Caution

Review remote scripts before running curl | bash or wget | bash in production.

Install Xanmod kernel

1. Check supported CPU level

   wget https://dl.xanmod.org/check_x86-64_psabi.sh
   chmod +x check_x86-64_psabi.sh
   ./check_x86-64_psabi.sh

2. Register Xanmod signing key

   wget -qO - https://dl.xanmod.org/archive.key | sudo gpg --dearmor -vo /etc/apt/keyrings/xanmod-archive-keyring.gpg

3. Add Xanmod repository

   echo 'deb [signed-by=/etc/apt/keyrings/xanmod-archive-keyring.gpg] http://deb.xanmod.org releases main' | sudo tee /etc/apt/sources.list.d/xanmod-release.list

4. Install kernel package

   sudo apt update && sudo apt install linux-xanmod-x64v3

5. Apply BBR tuning if your stack needs it, then reboot.

Limit ICMP response rate

Add stricter ICMP rate limits in /etc/sysctl.conf:

cat <<'EOT' | sudo tee -a /etc/sysctl.conf
net.ipv4.icmp_msgs_burst=1
net.ipv4.icmp_msgs_per_sec=1
net.ipv4.icmp_ratelimit=1
net.ipv6.icmp.ratelimit=1
EOT
sudo sysctl -p

Use this only after testing, because aggressive ICMP limits can complicate troubleshooting and network diagnostics.