bin/khatus_loop

   1 #! /bin/bash
   2
   3 MSG_TAG_SEP=': '
   4
   5 fetch_weather() {
   6     metar -d "$WEATHER_STATION_ID" 2>&1 \
   7     | awk '
   8         /METAR pattern not found in NOAA data/ {
   9             failures++
  10         }
  11
  12         /^Temperature/ {
  13             celsius = $3;
  14             fahrenheit = (celsius * (9 / 5)) + 32;
  15             temperature = fahrenheit
  16         }
  17
  18         END {
  19             if (failures > 0) {
  20                 temperature = "--"
  21             }
  22             print temperature "°F"
  23         }'
  24 }
  25
  26 fetch_datetime() {
  27     date +'%a %b %d %H:%M:%S'
  28 }
  29
  30 read_and_react() {
  31     pipe="$1"
  32     tail -f "$pipe" \
  33     | stdbuf -o L awk \
  34         '
  35             /^in:WEATHER:/\
  36             {
  37                 db["weather_temperature"] = read_msg()
  38             }
  39
  40             /^in:DATE_TIME:/\
  41             {
  42                 db["datetime"] = read_msg()
  43             }
  44
  45             /^out:BAR:/\
  46             {
  47                 print make_bar()
  48             }
  49
  50             function read_msg() {
  51                 sub("^" $1 " +", "")
  52                 return $0
  53             }
  54
  55             function make_bar(    position, bar, i) {
  56                 position[++i] = db["weather_temperature"]
  57                 position[++i] = db["datetime"]
  58                 bar = ""
  59                 sep = ""
  60                 for (j = 1; j <= i; j++) {
  61                     bar = bar sep position[j]
  62                     sep = " "
  63                 }
  64                 return bar
  65             }
  66         '
  67 }
  68
  69 trigger_bar() {
  70     echo ''
  71 }
  72
  73 spawn() {
  74     cmd="$1"
  75     pipe="$2"
  76     tag="$3"
  77     interval="$4"
  78     while true; do
  79         echo "${tag}${MSG_TAG_SEP}$($cmd)" > "$pipe"
  80         sleep  "$interval"
  81     done &
  82 }
  83
  84 main() {
  85     dir_bin="$1"
  86     dir_data="$2"
  87     pipe="$dir_data/pipe"
  88
  89     WEATHER_STATION_ID='KJFK'
  90
  91     rm -f "$pipe"
  92     mkfifo "$pipe"
  93
  94     spawn fetch_datetime "$pipe" 'in:DATE_TIME' 1
  95     spawn fetch_weather  "$pipe" 'in:WEATHER'   $(( 30 * 60 ))
  96     spawn trigger_bar    "$pipe" 'out:BAR'      1
  97     read_and_react       "$pipe"
  98 }
  99
 100 main $@