Skilllibrary linux-ubuntu-ops

install

source · Clone the upstream repo

git clone https://github.com/merceralex397-collab/skilllibrary

Claude Code · Install into ~/.claude/skills/

T=$(mktemp -d) && git clone --depth=1 https://github.com/merceralex397-collab/skilllibrary "$T" && mkdir -p ~/.claude/skills && cp -r "$T/10-cli-systems-and-ops/linux-ubuntu-ops" ~/.claude/skills/merceralex397-collab-skilllibrary-linux-ubuntu-ops && rm -rf "$T"

manifest: 10-cli-systems-and-ops/linux-ubuntu-ops/SKILL.md

source content

Purpose

Administer Ubuntu/Debian systems: package management, service control, log analysis, user management, and firewall configuration.

When to use this skill

installing, updating, or removing packages with
```
apt
```
diagnosing service failures with
```
journalctl
```
and
```
systemctl
```
configuring firewall rules with
```
ufw
```
or
```
iptables
```
managing users, groups, and file permissions

Do not use this skill when

writing systemd unit files from scratch — prefer
```
systemd-services
```
packaging software for distribution — prefer
```
packaging-installers
```
the task is shell scripting — prefer
```
bash
```

Procedure

Update package index —
```
sudo apt update
```
before installing. Use
```
apt list --upgradable
```
to review.

Install packages —

sudo apt install -y pkg1 pkg2

. Pin versions for servers:

sudo apt install nginx=1.24.0-1

Diagnose service —

systemctl status svc

, then

journalctl -u svc --since "10 min ago" --no-pager -n 50

Check resources —
```
df -h
```
(disk),
```
free -h
```
(memory),
```
ss -tlnp
```
(listening ports),
```
top -bn1 | head -20
```
.

Manage users —

sudo adduser --disabled-password deploy

sudo usermod -aG sudo deploy

Configure firewall —

sudo ufw allow 22/tcp

sudo ufw allow 443/tcp

sudo ufw enable

sudo ufw status verbose

Set up unattended upgrades —

sudo apt install unattended-upgrades

sudo dpkg-reconfigure -plow unattended-upgrades

Clean up —

sudo apt autoremove -y && sudo apt autoclean

Common diagnostics

# Why did a service fail?
journalctl -u myservice --since "1 hour ago" -p err --no-pager

# What is using port 8080?
ss -tlnp | grep 8080

# Disk usage by directory
du -sh /var/log/* | sort -rh | head -10

# Failed login attempts
journalctl _COMM=sshd --since today | grep "Failed"

# Kernel messages
dmesg --level=err,warn | tail -20

Decision rules

Always run
```
apt update
```
before
```
apt install
```
— stale indexes cause version mismatches.
Use
```
systemctl
```
not legacy
```
/etc/init.d/
```
scripts.
Prefer
```
ufw
```
over raw
```
iptables
```
unless complex NAT rules are needed.
Never run services as root — create a dedicated user or use
```
DynamicUser=yes
```
in systemd.
Use
```
journalctl
```
over manual log file tailing — it handles rotation and filtering.

References

Related skills

```
systemd-services
```
— writing unit files
```
ssh-tmux-remote-workflow
```
— remote server management
```
terminal-debugging
```
— process-level debugging