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machines.coaxmetal: strom-pair re-pairs controllers with a stale bond
A pad paired to another device in the meantime still shows Bonded here, so the
old script skipped it and it never reconnected (kept shutting down / rejoining
the other host). Target pads by what actually shows up in the scan (present and
advertising in pairing mode) rather than the bonded-device list, and clear any
stale bond before re-pairing. Pads already connected and working are left
alone.
author
lassulus
date
(Jul 25, 2026, 11:28 PM CEST)
commit
580cf8a2
580cf8a2f91b89c6292d6eeaa36083254a95bc6f
parent
26bc7800
26bc7800e31d0068753c91fe31e5f2f8fc7ca481
+41
-28
+41
-28
machines/coaxmetal/strom.nix
+41
-28
machines/coaxmetal/strom.nix
···
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# `ssh root@coaxmetal.r strom-pair`): put the pad in pairing mode (hold the
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# Xbox button to power on, then hold the small round sync button on the top
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# edge until the light flashes rapidly) and the script blocks until it pairs
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# that one fresh pad, then exits. Already-bonded pads are skipped, so just run
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# it again for the next controller. Bonded+trusted pads reconnect on their own
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# on every later boot. Pass a MAC (`strom-pair AA:BB:...`) to pair just one.
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# that one pad, then exits. A pad currently paired to another device is
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# re-paired here (its stale bond is cleared); a pad already connected and
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# working is left alone. Run once per controller. Bonded+trusted pads
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# reconnect on their own on every later boot. Pass a MAC to pair just one.
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strom-pair = pkgs.writeShellApplication {
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name = "strom-pair";
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runtimeInputs = [ pkgs.bluez ];
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text = ''
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-
# Find one not-yet-bonded Xbox pad, echoing its MAC (empty if none). A
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# foreground timed scan is reliable; a backgrounded `scan on` exits at once
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# without a tty and never actually scans.
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find_unpaired() {
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local m
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bluetoothctl --timeout 12 scan on >/dev/null 2>&1 || true
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mapfile -t cand < <(bluetoothctl devices 2>/dev/null | grep -i xbox | awk '{print $2}')
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for m in "''${cand[@]:-}"; do
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# Find one Xbox pad that is here right now (advertising in pairing mode)
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# and not already connected; echo its MAC (empty if none). We key off what
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# actually shows up in THIS scan, not the bonded-device list: a pad that
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# was since re-paired to another host still lingers as "bonded" here but
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# only appears in a scan when it is genuinely present and pairable.
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find_target() {
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local sl m
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local -a bonded present
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sl=$(mktemp)
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bluetoothctl --timeout 12 scan on > "$sl" 2>&1 || true
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mapfile -t bonded < <(bluetoothctl devices 2>/dev/null | grep -i xbox | awk '{print $2}')
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# MACs of xbox pads that showed up in this scan (present + advertising).
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mapfile -t present < <(
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{
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# freshly discovered pads announce their name
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grep -i xbox "$sl" | grep -oiE '([0-9a-f]{2}:){5}[0-9a-f]{2}'
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# known/bonded pads emit nameless RSSI lines; match their MAC in-scan
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for m in "''${bonded[@]:-}"; do
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[ -n "$m" ] && grep -qiF "$m" "$sl" && printf '%s\n' "$m"
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done
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} | sort -uf
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)
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rm -f "$sl"
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for m in "''${present[@]:-}"; do
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[ -n "$m" ] || continue
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bluetoothctl info "$m" 2>/dev/null | grep -q "Bonded: yes" && continue
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bluetoothctl info "$m" 2>/dev/null | grep -q "Connected: yes" && continue
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printf '%s\n' "$m"
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return 0
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done
···
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# Pair one pad. Xbox controllers use JustWorks pairing, which needs a
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# NoInputNoOutput agent held in the SAME bluetoothctl session as `pair`
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# (plus disable_ertm, set system-wide below). `connect` succeeds even when
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# pairing fails, so success is judged by "Bonded: yes", not by connect.
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# (plus disable_ertm, set system-wide below). Remove any existing bond
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# first: a pad re-paired to another host still shows bonded here but never
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# reconnects, and bluez refuses a fresh pair while that stale bond exists.
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# `connect` succeeds even when pairing fails, so success is judged by
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# "Bonded: yes", not by connect.
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pair_one() {
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local mac="$1"
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bluetoothctl remove "$mac" >/dev/null 2>&1 || true
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{
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echo "power on"
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echo "agent NoInputNoOutput"
···
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bluetoothctl power on >/dev/null 2>&1 || true
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# Single-pad mode: pair exactly the given MAC and exit.
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# Single-pad mode: (re)pair exactly the given MAC and exit.
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if [ -n "''${1:-}" ]; then
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if pair_one "$1"; then
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echo ">> paired, trusted, connected: $1"
···
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exit 1
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fi
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# Default: wait for one fresh (unbonded) pad, pair it, then exit. Run once
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# per controller; already-bonded pads are ignored so each run grabs the
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# next one.
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# Default: wait for a pad that is present and in pairing mode, (re)pair it,
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# then exit. Run once per controller. A pad that was paired to another
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# device in the meantime is re-paired here (its stale bond is cleared)
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# rather than skipped; a pad already connected and working is left alone.
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echo ">> put a controller in pairing mode: hold the Xbox button to power"
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echo " on, then hold the small round sync button on the top edge until"
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echo " the light flashes rapidly. Waiting... (Ctrl-C to abort)"
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while true; do
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echo ">> scanning..."
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mac=$(find_unpaired)
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# Show which Xbox pads are visible and whether they are already bonded,
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# so it's obvious if the pad is being detected at all.
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bluetoothctl devices 2>/dev/null | grep -i xbox | while read -r _ m _; do
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if bluetoothctl info "$m" 2>/dev/null | grep -q "Bonded: yes"; then
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echo " seen $m (already bonded, skipping)"
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else
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echo " seen $m (pairable)"
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fi
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done
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mac=$(find_target)
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if [ -n "$mac" ]; then
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printf '>> pairing %s ... ' "$mac"
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if pair_one "$mac"; then