Adding Counter in shell script

Question

I have below code in my shell script which will keep on sleeping if it doesn\'t finds any file. And it sleeps for half an hour but currently I don\'t have any counter like only

Answer 1

Here's how you might implement a counter:

counter=0
while true; do
  if /home/hadoop/latest/bin/hadoop fs -ls /apps/hdtech/bds/quality-rt/dt=$DATE_YEST_FORMAT2 then
       echo "Files Present" | mailx -s "File Present"  -r admin@host.com admin@host.com
       exit 0
  elif [[ "$counter" -gt 20 ]]; then
       echo "Counter: $counter times reached; Exiting loop!"
       exit 1
  else
       counter=$((counter+1))
       echo "Counter: $counter time(s); Sleeping for another half an hour" | mailx -s "Time to Sleep Now"  -r admin@host.com admin@host.com
       sleep 1800
  fi
done

Some Explanations:

• counter=$((counter+1)) - this is how you can increment a counter. The $ for counter is optional inside the double parentheses in this case.
• elif [[ "$counter" -gt 20 ]]; then - this checks whether $counter is not greater than 20. If so, it outputs the appropriate message and breaks out of your while loop.

Answer 2

Try this:

counter=0
while true; do
  if /home/hadoop/latest/bin/hadoop fs -ls /apps/hdtech/bds/quality-rt/dt=$DATE_YEST_FORMAT2 then
       echo "Files Present" | mailx -s "File Present"  -r admin@host.com admin@host.com
       break
  elif [[ "$counter" -gt 20 ]]; then
       echo "Counter limit reached, exit script."
       exit 1
  else
       let counter++
       echo "Sleeping for another half an hour" | mailx -s "Time to Sleep Now"  -r admin@host.com admin@host.com
       sleep 1800
  fi
done

Explanation

• break - if files are present, it will break and allow the script to process the files.
• [[ "$counter" -gt 20 ]] - if the counter variable is greater than 20, the script will exit.
• let counter++ - increments the counter by 1 at each pass.