Tails a remote file via HTTP. Polls the HTTP Headers, via curl, and when "Content-Length" has changed, fetches the remaining difference

bash-webtail

#!/bin/bash

POLLING_INTERVAL=2
CONTENT_LENGTH=0

while true
do

	FETCH_CONTENT_LENGTH=`curl -s -r 0-0 -I $1 | egrep -i "Content-Range" | cut -d/ -f2 | awk -F"\r" '{print $1}'`
	TMP_CONTENT_LENGTH=$FETCH_CONTENT_LENGTH


	if [[ $TMP_CONTENT_LENGTH > $CONTENT_LENGTH ]]
	then

		if [[ $CONTENT_LENGTH == 0 ]]
		then
			curl -s -r -500 $1
		else
			REMAINING=$CONTENT_LENGTH-$TMP_CONTENT_LENGTH
			curl -s -r $REMAINING $1
		fi
	
		CONTENT_LENGTH=$TMP_CONTENT_LENGTH
	fi

	sleep $POLLING_INTERVAL

done