One-liner: how to check file growth in real time

Not quite a one-liner, but it can be copy&pasted in a terminal window 😉

bash
TIME=10
FILE=file.log
function fsize {
	SIZE=`ls -l $FILE | awk '{print $5}'`
}
fsize
S1=$SIZE
while true
do
	sleep $TIME
	fsize
	S2=$SIZE
	(( DIFF=($S2-$S1)/$TIME ))
	echo "($S2-$S1)/$TIME = $DIFF"
	S1=$S2
done

The script above will check the “file.log” size every 10 seconds and output the previous size, the new size and bytes per second:

(30117062-30085517)/10 = 3154
(30148404-30117062)/10 = 3134
(30179199-30148404)/10 = 3079
^C
^D