Arch Btw

Arch BTW: Arch Linux and CachyOS Administration

Administer Arch Linux and Arch-style systems without falling into rolling-release footguns. Focus on vanilla Arch first, then layer in CachyOS behavior, paru workflow, systemd-native service management, boot recovery, kernel handling, and derivative-specific cautions.

Versions worth pinning (May 2026):

Only pin versions here when they materially affect compatibility or troubleshooting shape. For ordinary rolling packages, prefer the current repo state over stale version tables.

When to use

• Package management on Arch or CachyOS with pacman, paru, AUR builds, mirrorlists, or keyrings
• systemd service, timer, socket, boot, and journal troubleshooting on Arch-style systems
• Bootloader, initramfs, UKI, Secure Boot, kernel, and recovery work on Arch or CachyOS
• Rolling-release maintenance, .pacnew merges, orphan cleanup, foreign package audits
• CachyOS-specific repo, kernel, snapshot, or optimized-repo questions
• Desktop stack work on Arch-style systems: Wayland vs X11, Hyprland, KDE, GNOME, portals, PipeWire, Bluetooth
• Session startup and laptop work: GDM, SDDM, greetd, suspend or resume, power profiles, hybrid graphics
• GPU and gaming work: NVIDIA pain, AMD or Intel graphics, Vulkan, Steam, Proton, Gamescope, MangoHud, GameMode
• Capture and communication stack work: OBS, WebRTC screen sharing, Discord or Teams issues, portals, virtual cameras
• Storage and rollback work: Btrfs, Snapper, LUKS, TRIM, hibernation or resume, snapshot recovery limits
• Remote gaming and input work: Moonlight, Sunshine-style hosting, Steam Remote Play, controllers, Bluetooth pads
• Base Linux ops and CLI tooling on Arch-style systems: journalctl, dmesg, lsblk, findmnt, jq, ripgrep, bat, eza, nvim
• EndeavourOS or Manjaro tasks where the real problem is still Arch package, boot, or service behavior

When NOT to use

• Shell syntax, quoting, or script portability problems - use command-prompt
• Network architecture, DNS, VPNs, reverse proxies, or firewall design - use networking
• Docker, Podman, image builds, or container runtime issues - use docker
• Kubernetes cluster or manifest work - use kubernetes
• Fleet-wide Linux configuration via playbooks or roles - use ansible
• Security review, vulnerability triage, or offensive testing - use security-audit or lockpick
• OPNsense or pfSense appliance work - use firewall-appliance
• Nix/NixOS questions - use nixos-btw
• Debian, Ubuntu, Mint, or Pop!_OS administration - use debian-ubuntu
• RHEL, Fedora, CentOS, or AlmaLinux administration - use rhel-fedora
• Kali Linux and offensive-security tooling - use kali-linux

AI Self-Check

Before returning Arch or CachyOS commands, verify:

• No partial upgrades: do not suggest pacman -Sy <pkg> on Arch-style systems. Use a full upgrade path or stop.
• Distro identified first: Arch, CachyOS, EndeavourOS, and Manjaro are not interchangeable once repos diverge.
• Boot stack identified: know the bootloader, ESP mountpoint, kernel package, and initramfs generator before changing kernel or boot files.
• Fallback path exists: do not remove or replace the only known-good kernel or boot entry on a remote system.
• AUR trust boundary respected: review PKGBUILD and related files before building. Treat paru as convenience, not as proof of safety.
• systemd scope is correct: distinguish system units from user units and use systemctl --user only when appropriate.
• Wayland stack is coherent: compositor, portal backend, Xwayland compatibility, and user-session services line up.
• Session startup path is identified: display manager, greeter, or TTY launch path is known before debugging environment propagation or autostart.
• Audio stack is coherent: PipeWire, pipewire-pulse, and WirePlumber are not fighting a leftover PulseAudio setup.
• Bluetooth path is complete: bluetooth.service alone is not enough if audio routing, trust, pairing, or profile selection is broken.
• GPU stack matches the hardware: Mesa vs NVIDIA stack, Vulkan driver, firmware, and kernel module choice match the actual GPU vendor.
• Gaming stack includes 32-bit userspace when needed: Steam and Proton failures often come from missing multilib graphics pieces, not the game itself.
• Capture stack is coherent: portal backend, PipeWire, WebRTC or Electron client path, and any virtual camera module choice line up with the current session type.
• Suspend and rollback claims are real: hibernation, snapshots, and rollback advice matches the actual filesystem, boot path, and encryption layout.
• Version table is current: if the pinned version table is more than a few weeks old, verify critical versions (kernel, systemd, nvidia-utils) against pacman -Q before relying on them.
• CachyOS advice is not backported blindly: optimized repos, custom pacman behavior, snapshot defaults, and kernel tooling are CachyOS-specific.
• DKMS modules match the running kernel: after kernel changes, confirm that NVIDIA, v4l2loopback, and other out-of-tree modules are built for the current kernel before blaming the desktop, OBS, or Steam.
• Hybrid graphics path is identified on laptops: PRIME offload, muxless, or discrete-only mode affects display output, suspend behavior, and Gamescope compatibility. Do not assume single-GPU behavior on multi-GPU hardware.
• Diagnostic errors are not silenced: do not mask failures with 2>/dev/null on commands whose error reason matters for triage. Use 2>&1 || true to surface errors without aborting a gathering pass.
• Snapshots are not backups: on Btrfs systems, snapshots help with rollback but do not replace real backups.
• Conflicting files use exact path: --overwrite uses the specific file path from pacman error output, never a blanket '*' glob
• Current source checked: dated versions, CLI flags, API names, and support windows are verified against primary docs before repeating them
• Hidden state identified: local config, credentials, caches, contexts, branches, cluster targets, or previous runs are made explicit before acting
• Verification is real: final checks exercise the actual runtime, parser, service, or integration point instead of only linting prose or happy paths
• Routing overlap checked: overlapping skills, trigger terms, and "When NOT to use" boundaries are checked before returning guidance
• Spec claims verified: claims about tool behavior, output contracts, or repo conventions are checked against current docs, scripts, or skill files
• Mirror and repo state checked: package advice matches current Arch/CachyOS repos and local mirror sync status
• AUR trust handled: PKGBUILDs, install scripts, and maintainer changes are reviewed before build/install

Performance

• Use pacman -Syu before large installs to avoid partial-upgrade churn and repeated dependency resolution.
• Keep package cache cleanup deliberate; retain at least one known-good package version when rollback may matter.
• For slow mirrors, rank mirrors before troubleshooting package-manager performance.

Best Practices

• Never recommend partial upgrades on Arch-family systems.
• Snapshot or otherwise preserve rollback paths before kernel, bootloader, filesystem, or GPU driver changes.
• Read pacman hooks and .pacnew files after major updates; do not assume config merges happened automatically.

Workflow

Step 1: Identify the distro lane first

Step 2: Gather current system state

Start with a narrow fact-gathering pass before prescribing changes:

cat /etc/os-release
uname -r
pacman -Q pacman systemd
pacman -Qm
systemctl --failed
journalctl -b -p warning..alert
findmnt /boot
findmnt /efi
bootctl status
lsblk -f
echo "Session=$XDG_SESSION_TYPE Desktop=$XDG_CURRENT_DESKTOP"
loginctl list-sessions 2>&1 || true
systemctl status display-manager 2>&1 || true
systemctl --user --failed 2>&1 || true
systemctl --user status pipewire pipewire-pulse wireplumber 2>&1 || true
systemctl --user status xdg-desktop-portal 2>&1 || true
systemctl status power-profiles-daemon 2>&1 || true
command -v wpctl >/dev/null 2>&1 && wpctl status
command -v bluetoothctl >/dev/null 2>&1 && bluetoothctl show
pacman -Q obs-studio xdg-desktop-portal discord v4l2loopback-dkms 2>&1 || true
lspci -k | grep -Ei 'vga|3d|display'
journalctl -b | grep -Ei 'nvrm|nvidia|amdgpu|i915|xe|drm'
journalctl --user -b | grep -Ei 'portal|pipewire|webrtc|obs'
lsmod | grep '^v4l2loopback'
command -v dkms >/dev/null 2>&1 && dkms status
findmnt -t btrfs
systemctl status fstrim.timer 2>/dev/null || true
ls /etc/*.pacnew /etc/*.pacsave 2>/dev/null

If paru is present, prefer it for day-to-day AUR workflow. Fall back to raw makepkg and pacman -U when debugging build, key, or dependency issues.

Step 3: Load only the relevant reference

Do not load every reference by default. Pick the one that matches the failure mode.

Step 4: Change one layer at a time

• Fix package state before debugging services that may be broken by stale libraries.
• Fix service configuration before declaring systemd itself broken.
• Fix mountpoints and loader state before rebuilding initramfs or UKIs.
• mkinitcpio vs dracut: check pacman -Q mkinitcpio dracut to determine which is installed. mkinitcpio is Arch default; CachyOS may use dracut. Do not mix them - pick the installed one and use its config/hooks exclusively.
• On CachyOS, separate "vanilla Arch behavior" from "optimized repo or custom kernel behavior."
• Prefer reversible steps: snapshots, package cache, fallback kernels, saved configs.

Step 5: Validate before closing

pacman -Qk package_name
systemctl status unit_name
journalctl -u unit_name -b
bootctl status

Reboot only when the boot path is understood and at least one known-good entry remains.

Troubleshooting Pattern

Keep triage cross-layer and boring:

1. Confirm the active distro, session type, kernel, and package lane.
2. Identify the failing layer: package state, system service, user service, boot path, desktop session, graphics, or app.
3. Pull the right logs before changing config.
4. Change one layer at a time and retest.
5. Prefer a known-good baseline over tweak stacking.

Core log sweep:

journalctl -b -p warning..alert
journalctl --user -b
dmesg --level=err,warn
journalctl -u unit_name -b
journalctl --user -u pipewire -u wireplumber -u xdg-desktop-portal -b

Practical interpretations:

• journalctl -b is the broad system picture for the current boot.
• journalctl --user -b matters for Wayland, PipeWire, portals, and desktop-session failures.
• dmesg is where kernel and driver problems surface first, especially boot, storage, and GPU issues.
• Focused unit logs beat random reinstall churn.

When a bug looks "desktop-only," compare one clean baseline:

• GNOME or Plasma vs Hyprland
• browser WebRTC vs packaged client
• plain game launch vs Gamescope or MangoHud
• known-good kernel vs newly changed kernel

Default Decisions

• Arch means full upgrades. Package skew is often self-inflicted. Resolve sync state first.
• Use systemd-native tools first. Reach for systemctl, journalctl, bootctl, timedatectl, and localectl before distro wrappers.
• Use paru for convenience, not for trust. When an AUR package misbehaves, drop to PKGBUILD, makepkg, and the resulting package file.
• Treat kernel and boot work as one subsystem. Kernel package, initramfs generator, bootloader, microcode, and UKI signing all have to agree.
• CachyOS advice is branch-sensitive. Optimized repos and kernel variants can improve performance, but they add another compatibility layer to reason about.
• Desktop failures are often session failures. On Hyprland and other Wayland compositors, user units, portals, and session env matter as much as the package list.
• Gaming failures are often stack mismatches. Wrong GPU driver branch, missing multilib userspace, absent firmware, or a broken Proton path is more common than "Linux gaming is bad."

Quick Triage Checklist

Reference Files

• references/packages-and-aur.md - Arch package workflow, paru, manual AUR builds, keyring and mirror problems, .pacnew handling
• references/systemd-and-journal.md - systemd service debugging, unit overrides, user units, journal triage, and safe edit flow
• references/boot-kernel-and-recovery.md - kernel packages, mkinitcpio vs dracut, systemd-boot, UKIs, Secure Boot, and live-ISO recovery
• references/cachyos-and-derivatives.md - CachyOS optimized repos, custom kernels, snapshot defaults, and brief derivative guidance
• references/desktop-audio-and-bluetooth.md - X11 vs Wayland, Hyprland focus, GNOME and KDE notes, portals, PipeWire, and Bluetooth troubleshooting
• references/session-display-and-mobile.md - GDM, SDDM, greetd, session env, suspend or resume, power profiles, and hybrid graphics routing
• references/graphics-and-gaming.md - NVIDIA, AMD, Intel, Vulkan, Steam, Proton, Gamescope, MangoHud, GameMode, and why CachyOS gets attention from Linux gamers
• references/capture-and-sharing.md - OBS, WebRTC screen sharing, Discord and Teams routing, hardware encoding, and virtual camera troubleshooting
• references/storage-and-rollback.md - Btrfs, Snapper, LUKS, TRIM, hibernation, resume, and rollback boundaries
• references/remote-gaming-input-and-tooling.md - Moonlight, Sunshine-style hosting, controllers, and Steam Remote Play
• references/base-linux-and-cli.md - core Linux inspection commands and optional tools such as nvim, jq, ripgrep, bat, and eza
• references/gotchas-and-special-situations.md - recurring Arch and CachyOS failure patterns, special cases, and what-to-do-next guidance

Output Contract

See skills/_shared/output-contract.md for the full contract.

• Skill name: ARCH-BTW
• Deliverable bucket: audits
• Mode: conditional. When invoked to analyze, review, audit, or improve existing repo content, emit the full contract - boxed inline header, body summary inline plus per-finding detail in the deliverable file, boxed conclusion, conclusion table - and write the deliverable to docs/local/audits/arch-btw/<YYYY-MM-DD>-<slug>.md. When invoked to answer a question, teach a concept, build a new artifact, or generate content, respond freely without the contract.
• Severity scale: P0 | P1 | P2 | P3 | info (see shared contract; only used in audit/review mode).

Related Skills

• command-prompt - use it for shell syntax, zsh or bash behavior, and script portability
• networking - use it for network services, DNS, VPNs, and firewall design
• docker - use it for container runtime and image concerns instead of host distro administration
• ansible - use it when the real task is codifying Linux changes across many machines
• security-audit - use it for hardening and security review rather than normal package or service administration
• update-docs - use it after substantial system administration changes that introduce new operational gotchas
• nixos-btw - use it for Nix/NixOS systems; the declarative model and tooling are fundamentally different from Arch
• debian-ubuntu - use it for Debian, Ubuntu, Mint, and Pop!_OS administration
• rhel-fedora - use it for RHEL, Fedora, CentOS, and AlmaLinux administration
• kali-linux - use it for Kali Linux and offensive-security tooling

Rules

1. Identify the distro before prescribing commands. Arch, CachyOS, EndeavourOS, and Manjaro differ where it matters most: repos, wrappers, and recovery assumptions.
2. No partial upgrade advice. If the fix begins with pacman -Sy <pkg>, it is probably wrong.
3. Keep paru, but keep perspective. Use it as the default AUR helper because the user does, then drop to raw AUR packaging when the failure gets real.
4. Know the boot chain before touching it. Confirm loader, ESP, kernel package, initramfs generator, and signing path first.
5. Never remove the last known-good kernel path casually. Especially on remote or encrypted systems.
6. Prefer systemd-native diagnostics. systemctl, journalctl, and bootctl usually tell you more than distro wrappers or generic forum folklore.
7. CachyOS performance features are opt-in complexity. Treat optimized repos, custom kernels, and scheduler tooling as additions that must be validated, not magic defaults.
8. For Hyprland and Wayland issues, inspect the user session first. Portals, user units, and Xwayland compatibility usually matter more than package reinstall churn.
9. For gaming issues, identify the GPU vendor and userspace first. Driver branch, Vulkan stack, multilib, and launch wrappers usually explain more than random tweak cargo cults.
10. For Wayland capture issues, debug portals and PipeWire before app folklore. OBS, browser WebRTC, Discord, and Teams often fail at the screencast path, not at "Linux video" in general.
11. Treat display manager, lock screen, and idle helpers as separate layers. GDM, SDDM, greetd, hyprlock, and hypridle can fail independently.
12. Do not oversell snapshots or resume hooks. Btrfs rollback, hibernation, and encrypted-root recovery all depend on the exact boot and storage layout.
13. Reach for common Arch failure patterns before exotic explanations. Partial upgrades, DKMS drift, portal mismatch, stale AUR packages, and bad session startup explain a large share of the chaos.