simple wrapper around mosquitto_pub to make a line based pipe to a server+topic easier. Example usage: `fortune-loop | mlpub`

fortune-loop

#!/usr/bin/bash

DELAY_DEFAULT=5
DELAY=${DELAY:-$DELAY_DEFAULT}

if ! command -v fortune > /dev/null; then
  echo "missing fortune"
  echo "   fix: sudo apt install fortune-mod"
  exit 1
fi

while(true); do
  fortune
  echo
  sleep $DELAY
done

mlpub

#!/usr/bin/bash
# Dayne Broderson 2024

CMD_NAME=$(basename $0)
MQTT_HOST_DEFAULT="localhost"
MQTT_TOPIC_DEFAULT="${1:-"/$CMD_NAME"}"

MQTT_HOST="${MQTT_HOST:-$MQTT_HOST_DEFAULT}"
MQTT_TOPIC="${MQTT_TOPIC:-$MQTT_TOPIC_DEFAULT}"

if ! command -v mosquitto_pub > /dev/null; then
  echo "missing command: mosquitto_pub"
  echo "            fix: sudo apt install mosquitto-clients"
  exit 1
fi

if ! command -v nc > /dev/null; then
  echo "missing command: nc"
  echo "            fix: sudo apt install"
  sleep 3
else
  if ! $(nc $MQTT_HOST 1883); then
    echo "Warning: Unable to connec to $MQTT_HOST on 1883"
    echo "  possible fix: sudo apt install mosquitto"
    echo "                sudo /etc/init.d/mosquitto start"
    sleep 3
  fi
fi

display_help() {
  echo "Usage: $CMD_NAME"
  echo "    This script is intended to b e used in a pipeline"
  echo "    It reads from STDIN and publishes each line as a message to MQTT"
  echo "MQTT server & topic set via environment vairables"
  echo "    MQTT_HOST=$MQTT_HOST"
  echo "    MQTT_TOPIC=$MQTT_TOPIC"
  echo "Examples:"
  echo "    echo 'hi' | $CMD_NAME"
  echo "    cat file.txt | $CMD_NAME"
  echo "    MQTT_TOPIC='/new/topic' cat file.txt | $CMD_NAME"
  echo "    MQTT_HOST='127.0.0.1' cat file.txt | $CMD_NAME '/new/topic'"
}


# interactive script run check
if [ -t 0 ]; then
  display_help
  exit 1
else
  echo "Reading from STDIN and pushing to $MQTT_HOST at $MQTT_TOPIC"
  echo "  watch: mosquitto_sub -h ${MQTT_HOST} -t ${MQTT_TOPIC}"
fi

while IFS= read -r line; do
  mosquitto_pub -h "$MQTT_HOST" -t "$MQTT_TOPIC" -m "$line"
  if [ $? -eq 0 ]; then
    echo "published: $line"
  else
    echo "Error: mosquitto_pub failed"
    exit 1
  fi
done