Shell Programming and Scripting

Hello linuxuser_

Could you please let me know the following points.

i- Contents are updating daily in a sngle file or after creating a backup of old file it is creating a new one like as follows.
file_yesterday, file_today OR there is only 1 file.

ii- Also what is the time period when file is being updated? Is it a daily a fixed time task or not?

Also please add more information if there any it will help us to understand your actual requirement.

Thanks,
R. Singh

file content after 1st iteration

Code:

Time = 1

file content after 2nd iteration

Code:

Time = 1
Time = 2

file content after 3rd iteration

Code:

Time = 1
Time = 2
Time = 3

file content after 4th iteration

Code:

Time = 1
Time = 2
Time = 3
Time = 4

and so-on.
Hope it will clear all your questions.
Hint is I always have to search for last Time value and compare with previous value. If its get updated have to do some shell operations.

Regards
linuxUser_

Hello linuxuser_

You can use the following code for same. This is also an example of infinite loop which will break when it's condition gets satisfied(means file is being updated). Please run this in background and you can set it to crontab as per your need like 2 hours or 4 hours difference.

Code:

a=10;
cp -p file11 /tmp/file1 ## created copy of file at tmp
while [ $a -le $a ]
do
## comparing the values of files present in directory and in tmp ##

 value=`diff /tmp/file1 file11` 
  if [[ -n $value ]]
  then
   echo "file has been updated."
   rm /tmp/file1
   break;
  else
   sleep 120
  fi
done

Please let us know if you have any queries.

Thanks,
R. Singh

Thanks a lot
One very quick question:
will sleep 120 allow shell to check for the condition in mean time or it will make shell to sleep for 120 minutes?

In other way how should I come-up with correct value for sleep time? or its independent of time?

Thanks & Regards
linuxUser_

Hello linuxuser_

you can put sleep timings as per your wish lets say it is 2 mins then again it will check the condition either file has been updated or not if yes it will come out of loop else it will start sleep process again. So we need not to worry about condition check as it will happen only thing this sleep process will make us to set the time period like after how much time we need script to check about file's status. But if you will put less minutes lets say 1 min then it will keep server occupy to check the file status in every one min so better we can mention 5 mins or so(as per your wish as you would have better idea about file's updating timings) so that it will not occupy server that much which it will do when we will keep 1 min interval.


Thanks,
R. Singh

Dear Ravinder,

Need little help regarding the same problem.
Finally I got one conclusion that I should be able to read time value from the output file that will get update after every time step.

file format after some iterations:

Code:

Time = 0

xMin = 0.0
yMin = 0.0
xMax = 1.0
yMax = 1.0

Time = 1

xMin = 0.01
yMin = 0.01
xMax = 0.98
yMax = 0.899

Time = 2

xMin = 0.19
yMin = 0.25
xMax = 0.795
yMax = 0.9878

Time = 3

I want to read last time or last but-one depends on existence of some file for particular time step.
Can you help me?

Regards,
linuxUser_

Dear linuxuser_

Could you please be more clear on your requirement, as I understood you are requesting for checking a file's existance. Let me give you an example for same.

Code:

if [[ -f "file2" ]] 
then 
echo 
"file2 is present."
else 
echo "file2 is NOT present." 
fi

In my case file is present so it will give following output. Also please refer man test for more information. Hope this helps.

Code:

file2 is present.

Thanks,
R. Singh