Linux – Measuring ‘Total Bytes Written’ Under Linux

Don't know of an easier way off hand, but this bash snippet might help you with parsing out what you need from iotop:

iotop --batch --pid 1 > log
line_num=0
while read line; do 
    line_num=$(($line_n+1)) 
    if [[ $(($line_num % 3)) -eq 0 ]]; then 
        #print Column 3
        echo $line | awk '{print $3}'
    fi 
done < log > processed_file
#Get total of column three:
cat processed_file | (tr '\n' +; echo 0) | bc

Actually, Might be easier to read /proc/$PID/io every x seconds:

val=0
total=0
counter=0
pid=2323
while [[ $counter < 100 ]]; do 
    counter=$(($counter +1 ))
    #Change the sed number for different line, 5 is read_bytes
    val=$(cat /proc/$pid/io | sed -n '5p' | awk '{ print $2 }')
    total=$(($total + $val))
    echo $total 
    sleep 1 
done

Actually, looks like the above script is wrong, because it seems like /proc/<pid>/io is just the total, so really, just grab it once, wait however long, grab it again, find the differnce and there is your answer. You might want to look at the source code and find out its data type to see if it eventually wraps around. Probably not a problem for a little tablet though.

There is now an official way to do this in rsync (version 3.1.0 protocol version 31, tested with Ubuntu Trusty 14.04).

#> ./rsync -a --info=progress2 /usr .
    305,002,533  80%   65.69MB/s    0:00:01  xfr#1653, ir-chk=1593/3594)

I tried with my /usr folder because I wanted this feature for transferring whole filesystems, and /usr seemed to be a good representative sample.

The --info=progress2 gives a nice overall percentage, even if it's just a partial value. In fact, my /usr folder is more than 6 gigs:

#> du -sh /usr
6,6G    /usr/

and rsync took a lot of time to scan it all. So almost all the time the percentage I've seen was about 90% completed, but nonetheless it's comforting to see that something is being copied :)

References:

• https://stackoverflow.com/a/7272339/1396334
• https://download.samba.org/pub/rsync/NEWS#3.1.0