termux-device-automation

name	termux-device-automation
description	Use when scheduling cron jobs, sending termux-notification alerts, or setting up recurring watchers on this Termux device — especially when a notification silently never appears (exit 0, no error), crontab entries never fire, sv/crond won't start, or an F-Droid API poll misses fields.

Termux Device Automation (cron + notifications + API watchers)

Overview

Recurring automation on this device = cronie + termux-notification + a poll script. Every layer has a silent failure mode; this skill lists them with the verified fixes (all reproduced 2026-07-15).

Notifications: silent failure modes

termux-notification can exit 0 and deliver NOTHING. Differential diagnosis:

Symptom	Cause	Fix / test
exit 0, no notification	Android 13+ POST_NOTIFICATIONS denied for Termux:API app	Settings → Apps → Termux:API → Notifications → Allow
command hangs (needs timeout)	com.termux.api app not installed	pm list packages | rg termux (pm works unprivileged). Exit 0 + silence RULES OUT this case — missing app hangs, it never exits clean
everything above unclear	—	termux-toast "x" + termux-vibrate -d 400 use the same app but need no permission — if those work, it's the permission
INTERMITTENT: sometimes works, sometimes hangs/drops (perms fine, app installed)	Termux:API app frozen by battery optimization / phantom-process killing; broadcasts sit unserviced, clients hang forever	termux-api-start (starts its KeepAliveService) then retry; Settings → Apps → Termux:API → Battery → Unrestricted for a durable fix. In cron scripts ALWAYS timeout 25 termux-notification ... — hung clients pile up as zombies. Kill stuck ones: pgrep -fl "libexec/termux-api" then kill -9

dumpsys/appops are NOT accessible from Termux (no adb) — you can neither inspect nor grant the permission non-interactively; the Settings toggle is the only path. Use the toast differential to diagnose.

Cron: crond is not running by default

• cronie is installed; crontab -l may even show entries — but crond is dead and termux-services (sv, runsvdir) is absent despite $PREFIX/var/service/ existing. sv-enable crond fails silently.
• Fix: run crond directly (pgrep crond || crond).
• Boot persistence: ~/.termux/boot/crond.sh (already exists). Termux:Boot (must be installed AND opened once to activate) runs every file in ~/.termux/boot/; boot scripts need chmod +x and the absolute shebang below. Never append to startup.sh — it is a symlink into ~/git/operad/watchdog.sh and ends in a blocking while true loop; code after it never runs.
• Cron env is minimal: scripts need the absolute shebang #!/data/data/com.termux/files/usr/bin/bash AND export PATH=/data/data/com.termux/files/usr/bin:$PATH. Login-profile shims (the broken grep -G / curl functions) are NOT loaded in cron — plain curl is safe there.
• Verify the daemon actually executes jobs: install * * * * * touch $PREFIX/tmp/cron-probe, wait 70 s, check file, remove entry. ($PREFIX/tmp, never /tmp — unwritable on Termux.)

Working example: F-Droid release watcher

~/.local/bin/check-fdroid-cleverkeys.sh (crontab */10) — permanent new-version notifier. Pattern: poll API → compare against state file (~/.cache/fdroid-cleverkeys-last-code) → notify on increase → update state. First run seeds silently.

F-Droid API gotchas (f-droid.org/api/v1/packages/<appid>):

• suggestedVersionCode is top-level; suggestedVersionName does not exist. Match packages[] by versionCode and read its versionName: {"suggestedVersionCode": 104003, "packages": [{"versionName": "1.4.0", "versionCode": 104003}, ...]}
• Parse with python3 (json.load), not jq/grep, and wrap in try/except printing a sentinel — cron has no stderr you'll ever see.

Common mistakes

• Trusting exit 0 from termux-notification → always confirm delivery once per device.
• One-shot watchers that self-disarm when a permanent one was wanted (or vice versa) — decide explicitly; state-file compare gives permanent, marker-file + crontab self-removal gives one-shot.
• Editing startup.sh for boot tasks (blocking loop + foreign repo) — separate file in ~/.termux/boot/.