File locations

Where DisplaySync stores things and why. If you're tailing logs, hunting a stale config, or recovering after a reinstall, this is your map.

The desktop sign uses a single application data root for everything sign-specific (logs, database, identity, config, cache). On Windows, that root lives under C:\ProgramData\ rather than per-user %APPDATA% because the kiosk auto-login user shouldn't own files that survive a re-image. On Linux, the equivalent is /var/lib/.

Application data root

The sign app picks the data root using a priority list resolved at startup. The first writable candidate wins:

Platform	Path	Selection priority
Windows	`C:\ProgramData\DisplaySync\`	First — installer-managed, machine-wide
Linux	`/var/lib/displaysync/`	First on Linux
Dev fallback	`<repo>/data/`	When neither above is writable

The installer creates the Windows path and grants the kiosk user write access; on Linux the package manager handles /var/lib/displaysync/.

Inside the data root

Path	Purpose	Created by
`logs/sign.log`	Main runtime log (rolling)	`LogService`
`logs/error.log`	Errors only (companion file)	`LogService`
`database/sign.db`	SQLite — content cache, history	`DatabaseService`
`sign-config.json`	Identity + runtime flags (`monitoringMode`, `currentUrl`, `signId`, `shortCode`, etc.)	`ConfigService`
`.maintenance`	Sentinel file — watchdog skips relaunch when present	Manual or USB recovery script
`cache/`	Electron / web-content cache	Electron

External paths

Path	Purpose	Notes
`C:\ProgramData\Tailscale\`	Tailscale state (node identity, derp prefs)	Created by Tailscale installer
Task Scheduler → `\Microsoft\Windows\TaskScheduler\DisplaySync Sign\`	Watchdog scheduled task	Created by USB recovery `setup.ps1` — see USB recovery → Setup script
USB drive root: `setup.bat`, `setup.ps1`, `config.json`, etc.	USB recovery template	Six files documented in Building the drive

Sentry release ID

Errors that surface in Sentry from a kiosk carry a release tag in the format:

displaysync-sign@<version>

For example, a v1.3.1 sign reports its release as [email protected]. This is set by desktop-sign's Sentry initialization. See Error codes → Sentry tags and context for the rest of the Sentry context fields.

Linux differences

The desktop sign on Raspberry Pi / Linux follows the same layout under /var/lib/displaysync/:

logs/sign.log and logs/error.log — same names, same purpose
database/sign.db — SQLite, same schema
sign-config.json — same fields
No watchdog scheduled task — systemd is the equivalent (displaysync-sign.service)
No Tailscale C:\ProgramData\ — Tailscale state on Linux lives under /var/lib/tailscale/

See Linux & Raspberry Pi for the Linux-specific install layout.

How to find these in a hurry

Windows kiosk (RDP / VNC / local keyboard):

# Open Explorer at the data root:
explorer "C:\ProgramData\DisplaySync"

# Tail the live log:
Get-Content "C:\ProgramData\DisplaySync\logs\sign.log" -Wait -Tail 50

# Show errors only:
Get-Content "C:\ProgramData\DisplaySync\logs\error.log" -Tail 100

C:\ProgramData\ is hidden by default in Explorer's address bar — paste the full path or enable "Show hidden items" under the View tab.

Linux:

# Tail the live log:
sudo tail -f /var/lib/displaysync/logs/sign.log

# Show errors only:
sudo tail -100 /var/lib/displaysync/logs/error.log

Log locations — when to tail what, how to search
USB recovery → Setup script — what the recovery script wipes (the data root) and what it leaves alone
Installing DisplaySync — the install step that creates the data root
Remote control → Monitoring mode — sign-config.json carries the persisted monitoringMode flag