get-temperature

#!/bin/bash
# -*- coding: utf-8 -*-
# Wrapper for pcsensor https://github.com/peterfarsinsen/pcsensor.git
# This script extracts temperature from CSV and prints a JSON string as
# required by ScriptThermometer class of Thermod daemon.
#
# @author     Simone Rossetto
# @copyright  2016 Simone Rossetto
# @license    GNU General Public License v3
# @contact    simros85@gmail.com
# @version    1.0
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

# init variables
DEBUG=0
LANG=POSIX
PCSENSOR='/usr/local/bin/pcsensor -c -s'
PYMODULE='thermod.temperature'

# check required programs
REQUIRED_PROGRAMS=( logger cut printf )
for prog in ${REQUIRED_PROGRAMS[@]}; do
  if ! hash "$prog" 1>/dev/null 2>/dev/null; then
    echo -n "{\"error\": \"required program ${prog} not found\", \"temperature\": null}"
    exit 255
  fi
done

# parsing arguments for debug option
while :; do
  case $1 in
    -d|--debug) DEBUG=1 ;;
    *) break
  esac
  shift
done

# logging function
log()
{
  if [ "${1:-debug}" != 'debug' ]; then
    logger -t "${PYMODULE}" -i -p user.$1 -- "${1^^} ${2:-no message reported}"
  elif [ ${DEBUG} -eq 1 ]; then
    logger -t "${PYMODULE}" -i -p user.debug -- "DEBUG ${2:-no message reported}"
  fi
}

# main
log debug "querying thermometer using program '${PCSENSOR}'"
CSV=$(${PCSENSOR})

RET=$?
if [ ${RET} -ne 0 ]; then
  log debug "pcsensor exited with error code ${RET} and message '${CSV}'"
  printf '{"error": "%s", "temperature": null}' "${CSV}"
  exit ${RET}
fi

log debug "extracting temperature from CSV output '${CSV}'"
TEMPERATURE=$(echo -n "${CSV}" | cut -d \; -f 4)

RET=$?
if [ ${RET} -ne 0 ]; then
  log debug "cannot extract temperature from CSV: '${TEMPERATURE}'"
  printf '{"error": "%s", "temperature": null}' "${TEMPERATURE}"
  exit ${RET}
fi

log debug "converting temperature '${TEMPERATURE}' to number"
JSON=$(printf '{"temperature": %.2f, "error": null}' "${TEMPERATURE}")

RET=$?
if [ ${RET} -ne 0 ]; then
  err="cannot convert temperature '${TEMPERATURE}' to number"
  log debug "${err}"
  printf '{"error": "%s", "temperature": null}' "${err}"
  exit ${RET}
fi

log debug "$(printf 'current temperature is %.2f' "${TEMPERATURE}")"
echo -n "${JSON}"
exit 0

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