Batocera Ops

Batocera Ops

Foundation for operating a Batocera cabinet with a coding agent over SSH. Read this first; the sibling skills (batocera-roms, batocera-display, batocera-tuning, batocera-maintenance) assume the connection pattern, path model, and safety doctrine defined here.

Overview

Batocera is an immutable-rootfs Linux distro for retro gaming. The system partition is read-only; everything you can change lives under /userdata. EmulationStation (ES) is the frontend; RetroArch and standalone emulators do the playing. Configuration is layered: a single batocera.conf holds most settings, but launch-time code (configgen) regenerates per-emulator configs on every launch, so hand-edits to the generated files get stomped. Getting these two facts right prevents most wasted sessions.

Connecting

Batocera defaults to password SSH (no key from a fresh client). Parameterize the host so nothing is hardcoded:

export BATOCERA_HOST=192.168.1.50   # your cabinet's LAN IP

Batocera's documented default credentials are root / linux. If yours still uses them, change the password (ES menu → System Settings → Security, or passwd over SSH) — a machine you SSH into as root should not ship with a published password. The examples below read the password from an env var so it never lands in shell history or a committed file:

export BATOCERA_PASS='linux'   # replace with your actual password

# convenience wrapper used throughout these skills
SSHB() { sshpass -p "$BATOCERA_PASS" ssh -o StrictHostKeyChecking=no "root@$BATOCERA_HOST" "$@"; }
SCPB() { sshpass -p "$BATOCERA_PASS" scp -o StrictHostKeyChecking=no "$@"; }

Run a command: SSHB 'cat /usr/share/batocera/batocera.version' Copy down: SCPB "root@$BATOCERA_HOST:/userdata/screenshots/x.png" . Copy up: SCPB ./file "root@$BATOCERA_HOST:/userdata/system/"

If key auth is set up, drop sshpass. Batocera drops idle SSH connections; for long-running work use nohup … & or screen/tmux if installed. Rapid reconnects can trip the SSH daemon's throttle (transient "Permission denied"); wait a few seconds and retry rather than assuming the password is wrong.

The filesystem model

• Rootfs is read-only. You cannot persist edits to /usr, /etc, or /bin. Anything you write there vanishes on reboot (or fails outright).
• /userdata is the only writable tree. ROMs, configs, saves, BIOS, decorations, shaders, scripts, logs — all under /userdata.
• Do work on the box, not over an SMB mount from another machine — the cabinet's own tools (chdman, 7z, python3) are already present and paths line up. Python 3 is available; there is no compiler.

Key paths

batocera-conf precedence, the configgen regeneration model, and where a setting must live to survive a launch are in references/batocera-conf.md. The log inventory and ES restart mechanics are in references/emulationstation.md.

Safety doctrine

This is a shared physical device, often the family/party arcade cabinet. Treat it accordingly.

1. Non-destructive first. Read before you write. Prefer hiding to deleting, moving to removing, appending to overwriting. /userdata is the only thing standing between you and a re-image.
2. Back up before you touch a config or gamelist. One line, every time: SSHB 'cp /userdata/system/batocera.conf /userdata/system/batocera.conf.bak-$(date +%Y%m%d-%H%M%S)' Same for any gamelist.xml before editing it.
3. Never inject synthetic input. Do not use uinput virtual keyboards, xdotool, evemu, or virtual gamepads to "drive" the cabinet. Someone may be physically holding the controller; injected keypresses land in their open menu and silently change settings. If a test needs button/stick input, describe the exact steps and ask the human to drive. (The ES HTTP API launch below is not synthetic input — it is a documented control endpoint — but it does commandeer the screen, so skip it if someone is playing.)
4. Verify against ground truth, not assumption. After a change, re-read the file or launch the game and look. "It should work" is not evidence. See the verify loop below.

Remote verify loop (no controller needed)

The signature agent-native capability: change a display/config setting and confirm it end-to-end without touching the cabinet, using the ES HTTP API to launch and batocera-screenshot to see the result.

# 1. Launch a specific ROM via the ES HTTP API (runs ON the box, port 1234).
#    Works even for files ES doesn't list in its menu.
SSHB "curl -s -m3 -X POST http://127.0.0.1:1234/launch -d '/userdata/roms/<system>/<rom>'"

# 2. Wait 20-45s. Title/attract screens can be slow; if the shot is black,
#    take a second one a few seconds later before concluding anything.

# 3. Capture the framebuffer (this exact command; there is no swissknife
#    --screenshot). Writes a PNG into /userdata/screenshots/.
SSHB "batocera-screenshot"

# 4. Kill the running emulator, copy the newest screenshot down, and look at it.
SSHB "batocera-es-swissknife --emukill"
SCPB "root@$BATOCERA_HOST:/userdata/screenshots/$(SSHB 'ls -t /userdata/screenshots | head -1')" /tmp/verify.png
# then Read /tmp/verify.png

Config assertions after a libretro launch: the actual values RetroArch ran with are in /userdata/system/configs/retroarch/retroarchcustom.cfg and .../cores/retroarch-core-options.cfg, reflecting the last launch. Read those to confirm a key landed, rather than trusting that your batocera.conf edit took effect.

Gotchas that waste a verify session:

• Piping RetroArch's output swallows it. retroarch … | grep / | tail discards core errors silently. To see why a core failed, launch with --log-file /tmp/ra.log and read the file.
• A stray manually-run retroarch blocks ES launches — the ES launch exits instantly (~24ms, empty stderr, status 1). SSHB 'killall -9 retroarch' first.
• Gamelist edits need ES stopped. ES rewrites gamelist.xml on exit and clobbers live edits. Stop it (/etc/init.d/S31emulationstation stop) or use the SIGKILL-restart pattern in the emulationstation reference. Config edits to batocera.conf do not need this; gamelist XML edits do.
• Check what ES actually lists via the API: SSHB "curl -s http://127.0.0.1:1234/systems/<system>/games" (returns name/path/hidden per entry).

Provenance and freshness

Batocera changes across releases (path renames, custom.sh → services, new systems). These skills were distilled on v41-v43; commands are read-only unless noted. Before trusting a version-specific claim, confirm the build: SSHB 'cat /usr/share/batocera/batocera.version'. The canonical manual is the Batocera wiki; these skills capture operational lessons the wiki doesn't, not a replacement for it.