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 execute the below code 20 times and then exit the program if the files are still are not there  means don t do anything after 20 checks and exit the full script    What s the best way to do this problem  So that I am also aware by looking at the emails that it has tried 20 times   Hope I am clear enough   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   else        echo  Sleeping for half an hour    mailx -s  Time to Sleep Now   -r admin host com admin host com        sleep 1800   fi done

User · Answer

You may do this with a for loop instead of a while  max loop 20 for   count   0  count  lt  max loop  count      do   if  home hadoop latest bin hadoop fs -ls  apps hdtech bds quality-rt dt  DATE YEST FORMAT2 then        echo  quot Files Present quot    mailx -s  quot File Present quot   -r admin host com admin host com        break   else        echo  quot Sleeping for half an hour quot    mailx -s  quot Time to Sleep Now quot   -r admin host com admin host com        sleep 1800   fi done  if    quot  count quot  -eq  quot  max loop quot     then   echo  quot Maximum number of trials reached quot   gt  amp 2   exit 1 fi

User · Answer

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

User · Answer

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

[bash] Adding Counter in shell script

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