I have the following loop to view changing dir size:
while true; do du -hcs . ; sleep 2 ; clear ; done
What I'm not happy with is the waiting time between the clear and the actual output of du. The result is more or less a blinking number.
How can I modify this to simply write the new number over the old, with no black screen in between?
watch du -hcs .
From the man page:
watch runs command repeatedly, displaying its output (the first screenfull). This allows you to watch the program output change over time. By default, the program is run every 2 seconds; use
-nor--intervalto specify a different interval.
watch is smart: it only redraws the parts of the screen that have changed, avoiding the full screen clears that cause the blinking you see with clear.
watch is Linux only. Not on BSDI think that watch is the correct tool for what you are looking for, but
while true;do echo -n $(date +%Y%m%d%H%M%S) $(du -hcs ..|grep -v total);sleep 1;echo -e "\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b";done
might be just the poor substitute that you are looking for.
If, however your shell is dash rather than bash, then use:
while true;do echo $(date +%Y%m%d%H%M%S) $(du -hcs ..|grep -v total)|tr -d '\n';sleep 1;echo $'\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b';done
echo $0 to check.while true;do echo $(du -hcs ..|grep -v total)|tr -d '\n';sleep 1;echo $'\b\b\b\b\b\b\b\b\b\b';done ?