Reading telemetry data and applying an action

Faki · 06-06-2022, 12:05 AM

I have the following line that reads telemetry data from a logfile when File: or + is encountered. I am setting the variable action to either continue or break, then running the command after the last + entry. It seems a bit confusing when the action gets executed upon reaching (*). What can I do to make the intent clear?

Code:

  
  action="continue"

  while IFS= read -r telemetry; do

    attrib="${telemetry%[[:blank:]]*}" 
    
    case $attrib in
     ("File:")
               # "File:" field name has been reached.
               field="File" ; action="break" ;;
     ("+")
               # Detected the + continuation character
               [[ "$field" == "File" ]] && action="break" ;;
     (*)
               # action="continue"
               #   Ends current iteration, resuming at next iteration.
               #   Read next line in logfl, because "File" not yet reached.
               # action="break"
               #   Ends current iteration, exiting from the while loop.
               #   Exit logfl reading after end of field "File".
               $action ;;
    esac

  done < "$logfl"

michaelk · 06-06-2022, 05:55 AM

The *) matches anything so your loop will break for any line after action=break but you have set action="break" for both File

and +) cases. If you want to break at a + then why not just break at the +) case.

Quote:

after the last + entry.

If you have multiple lines that are the same in the log file then without knowing all the details would not this find the first occurrence and not the last?

Faki · 06-06-2022, 01:21 PM

The action=break does not execute the action, only when reaching *) do the commands continue and break execute.

One can either have

Code:

File: Value

or

Code:

File: Value
+ Value
+ Value
+ Value

The task is to capture the values for the File field.

If + is encountered, I will read through all subsequent values until the last + in encountered.

michaelk · 06-06-2022, 02:34 PM

Does it work as expected?

Faki · 06-06-2022, 02:39 PM

I feel it is implemented in a weird way.

michaelk · 06-06-2022, 02:44 PM

If it is commented enough then you should be able to come back 2 years from now and be able to understand how it works. You could do the same thing with an if-then-else too.