Shell Programming and Scripting

... just curious --- what is the exact command line did you use to do the "wc -l"?

The script is:

Code:

wc -l file1 | grep EXACTO > my_file
sleep5
wc -l file1 | grep EXACTO >> my_file

so in my_file i get the number of lines, the difference between those are what i need but it takes too much time.

any other idea?

Do you have control of the process writing these logfiles? If so you could just timestamp the log entries....

Or, you could write a script that will mark the logfile every 5 seconds by adding a line that's simle to search for and contains the time...

<------- 06/15/2005 15:27:35 --------->

the problem is that i cannot alter those file cuz is used to generate statistics

the problem here is that you are re-reading the file to grep out EXACTO after you read it the first time to count how many lines it has ... if the first read takes 3 seconds, the second read will probably takes just as long if not longer even though you really only need to read it once ...

... just grep out EXACTO from file1 then do the rest of the code i put in ... try it out and let us know if it helps or not ...

Code:

grep EXACTO file1 >> file2
currcnt=0
oldcnt=0
while true
do
    currcnt=$(wc -l file1 | awk '{print $1}')
    if [ $currcnt -ne $oldcnt ]
    then
        sed "1,${oldcnt}d" file1 | grep "EXACTO" >> file2
        oldcnt=$currcnt
    fi
    sleep 5
done

It works but it is still slow... there is not a way to do it with 'tail whatever'?

I did not quite understand how free are you to interfere with the file.
If you cannot catch it when it is written, may be you could pipe the output of "tail -f file1" to the program in C that would sleep for 5 secs, then print a timestamp and all lines it can read and sleep again? There still may be problems with timing mentioned by Jim M. but you may get some idea about what's going on.