I am trying to implement a timer for 5mins(300secs) in millisecons, but it is taking more than 5 minutes for sleep 0.001.
If I change if [ $t -ge 300000 ] to if [ $t -ge 30000 ], it is completing within 3 minutes.
df1, df2 holds the value of disk usage value at time t1 and t2 respectively.
t=0 x=0 df1 while [ $x -lt 10000 ] sleep 0.001 df2 x=(( df1-df2 )) if [ $t -ge 300000 ] then t=0 df1 else (( t++ )) fi done dosomething I want test $x for every 0.001secs. df1 and df2 should hold new values for every 300 secs. how can I achieve this?
3 Answers
date %N, will get time in nano seconds, maybe this help
start_at=$(date +%s,%N) _s1=$(echo $start_at | cut -d',' -f1) # sec _s2=$(echo $start_at | cut -d',' -f2) # nano sec # do somethong here end_at=$(date +%s,%N) _e1=$(echo $end_at | cut -d',' -f1) _e2=$(echo $end_at | cut -d',' -f2) time_cost=$(bc <<< "scale=3; $_e1 - $_s1 + ($_e2 -$_s2)/1000000000") I'm pretty sure that a single sleep like yours does not take several minutes. While it can and, in general, will take longer than the milisecond which you requested, the real sleep time should still be well below one second, or, if the system is heavily loaded, at most a couple of seconds.
One flaw in your application is that you don't take into account how long one iteration of your loop takes. You can't know this in advance; you only know that it will be longer than a milisecond, but not how much longer. Hence, you should end the loop after a certain time has passed - i.e. storing the start time somewhere and comparing the current time to the start time.
A second problem is that you don't set anywhere the variables df1 and df2, but maybe you left out this detail because you didn't consider it relevant for your question.
If you are looking for a countdown timer which displays milli-sec, you are looking for this.
This shows timer to hundredth of a second.
Change the logic as required.
timer() { time="`date '+%H:%M:%S' -d "$1"`" if [ $# -gt 0 ] && [ "$1" = "$time" ]; then echo IFS=: set -- $* secs=$(( ${1#0} * 3600 + ${2#0} * 60 + ${3#0} )) while [ $secs -ge 0 ]; do for msec in {99..0}; do printf "\rCountdown Timer: %02d:%02d:%02d:%02d" $((secs/3600)) $(( (secs/60)%60)) $((secs%60)) $((msec)) sleep .01 done secs=$(( $secs - 1 )) done echo fi echo } Usage: # timer HH:MM:SS Where: HH Time in Hours MM Time in Mins SS Time in Secs Example: # timer 00:10:00 Sets a countdown timer for 10 mins while displaying hundredth of a second. 
