Making a stopwatch function

Shell Programming and Scripting
1

#The first part of this works fine a period prints every 15 seconds (ping �c 3, takes 2 seconds). However no �Minutes since start = � message prints.

#By all rights it should print 2 times once when it is outputted from �grep� and a second time when cat reads it. I would use cron but I am not sure how to make cron work the way I need it to for this program, I need a stopwatch that notifies every 60 seconds, 5 minutes, 20 minutes etc�

#I know this is a roundabout method but I am still pretty new to UNIX so go easy on me. Other methods of doing this would be great but I would really appreciate help getting this to work as it would give me a better understanding.

#The script is as follows..

:

# Contained test of principal
#
cnt=0
while [ $cnt -lt 600 ]
 do
    while [ $cnt -lt 300 ]
     do
      echo .
      ping -c 3 not_connected_IP>>/tmp/pinglog$$.txt
      sleep 13
      ((cnt=cnt+15))
     done

    while [ $cnt -lt 300 ]
     do
      echo -n "Minutes since start = " > divres
      echo "scale=2; $cnt/60" | bc >> divres
      if cat divres | grep .00
       then
        echo
        cat divres
      fi
     done
 done
rm -r /tmp/pinglog$$.txt
2

Let's follow the logic here.

cnt=0
while [ $cnt -lt 600 ]
 do

    while [ $cnt -lt 300 ]
     do
      echo .
      # Instead of opening pinglog$$.txt n/15 times, redirect the
      # while loop itself, so you only open it once.
      ping -c 3 not_connected_IP#>>/tmp/pinglog$$.txt
      sleep 13
      ((cnt=cnt+15))
      # Jumps back up to the top of the loop if cnt is less than 300.
     done >> /tmp/pinglog$$.txt

    # to reach here, the while loop must have ended.  Therefore, 
    # cnt is already >= 300.  So this next while loop never happens.
    while [ $cnt -lt 300 ]
     do
      echo -n "Minutes since start = " > divres
      echo "scale=2; $cnt/60" | bc >> divres

#      this is a Useless Use of Cat.  http://partmaps.org/era/unix/award.html
#      grep doesn't need cat's help.
#
#      You should also use grep -q so grep doesn't try print matching lines.
#      Also:  Are you trying to match a literal dot?  dots mean 'any character'
#      grep.  Escape it with a backslash to make it match only the dot char.
#      if cat divres | grep .00
       if grep -q "\.00" < divres
       then
        echo
        cat divres
      fi
     done

     # Loops back to the beginning of the first while loop whenever
     # cnt is less than 600.
     # But cnt will never be greater than 300 because your inner
     # while loops stop doing anything past 300.
     # so this becomes an infinite loop!
 done
rm -r /tmp/pinglog$$.txt

I don't know how to simplify or fix a lot of this since I don't know what you were actually trying to do with it either.

3

Sorry, maybe I should clarify (I was at work, couldn't spend a lot of time on the forum). I want the program to print a period every 15 seconds that ping does not reach the host. Then every 60 seconds I want the second loop to print the contents of the divres which will say
"Minutes since start = ?.00
I have grep searching for ".00" because I want only the integer values when $cnt is divided by 60 anything but the minutes will show a decimal.
I go on in the rest of the program to apply the same principal from 900 - 1800 (value of $cnt) seconds and then -gt 1800 seconds.

Also I should have looked, this came from an earlier version the sleep time in the first loop should only be 2 seconds, because 3 failed pings actually take a rough average of 13 seconds.

I should have also included that the whole thing is contained in a while loop that looks for the output of 3 successful pings in pinglog.txt

I guess I need to practice my posting some too ey.

Thanks for your reply (and patience)

4

What is your system? If you have GNU ping, it can do that all by itself.

ping -w 15 -f mysite.com

Every 15 seconds, it will print one "." and backspace it if/when it gets a reply. The -c 4 will limit it to 4 pings and therefore one minute.

There's far better ways to do math in the shell, but which one you should use depends on what your system and shell is...

1 Like
5

Thanks everybody I ended up reformatting to include everything in one while loop after realizing that my linear process was messed up by trying to put everything in its own loop.
Thanks Corona I did not know about some of the functions of ping, I just figured it was pretty simple.