#!/bin/bash
rm result
echo 3 > /proc/sys/vm/drop_caches
sync;
echo start
nohup time dd if=/dev/zero of=mem bs=1M count=2000 &
for i in {1..200}
do
  sleep 0.2
  cat /proc/meminfo | grep Dirty >> result
  cat /proc/meminfo | grep Dirty
done
cat nohup.out
cat result

Dirty:                20 kB
Dirty:                20 kB
Dirty:                20 kB
Dirty:                20 kB
Dirty:                20 kB
Dirty:                24 kB
Dirty:                24 kB
Dirty:                24 kB
Dirty:                24 kB
Dirty:                28 kB
Dirty:                28 kB
Dirty:                28 kB
Dirty:                28 kB
Dirty:                28 kB
Dirty:             16528 kB
Dirty:            140608 kB
Dirty:            277228 kB
Dirty:            311768 kB
Dirty:            434308 kB
Dirty:            563352 kB
Dirty:            690952 kB
...

time dd if=/dev/zero of=mem bs=1M count=2000

#!/bin/bash
clear
while true
do
  sleep 0.2
  tput home
  cat /proc/meminfo
done

nohup time dd if=/dev/zero of=mem bs=1M count=2000 &

/bin/bash -x /path/to/script