Introduce script to update any var

* To make the manual build id / kernel tag update slightly less manual

Usage:
update-any-var.sh build_id SQ3A.220705.003 oriole raven # For Pixel 6 Jul 2022

TODO: Full automation
Change-Id: Iea350df2653c623b8f8476de4aec9cd1f7461c45

pixel/update-any-var.sh

@@ -0,0 +1,73 @@
+#!/bin/bash
+#
+# update-vars:
+#
+#   Update Pixel device-specific variables by parsing Google's pages
+#
+#
+##############################################################################
+
+
+### SET ###
+
+# use bash strict mode
+set -euo pipefail
+
+
+### TRAPS ###
+
+# trap signals for clean exit
+trap 'error_m interrupted!' SIGINT
+
+### CONSTANTS ###
+readonly script_path="$(cd "$(dirname "$0")";pwd -P)"
+readonly vars_path="${script_path}/../../../vendor/lineage/vars"
+
+source "${vars_path}/pixels"
+
+## HELP MESSAGE (USAGE INFO)
+# TODO
+
+### FUNCTIONS ###
+
+
+
+# error message
+# ARG1: error message for STDERR
+# ARG2: error status
+error_m() {
+  echo "ERROR: ${1:-'failed.'}" 1>&2
+  return "${2:-1}"
+}
+
+# print help message.
+help_message() {
+  echo "${help_message:-'No help available.'}"
+}
+
+main() {
+  local key="${1}"
+  local value="${2}"
+  shift; shift
+  if [[ $# -ne 0 ]]; then
+    local files="${@}"
+  else
+    local files="${devices[@]}"
+  fi
+
+  for f in ${files}; do
+    (
+      local fv="${vars_path}/${f}"
+      source "${fv}"
+      sed -i "/ prev_${key}=/c\readonly prev_${key}=\"${!key}\"" "${fv}"
+      sed -i "/ ${key}=/c\readonly ${key}=\"$value\"" "${fv}"
+    )
+  done
+}
+
+### RUN PROGRAM ###
+
+main "${@}"
+
+
+##