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Full Discussion: Count lines and words of a stream output with tail
Top Forums Shell Programming and Scripting Count lines and words of a stream output with tail Post 302865509 by alister on Friday 18th of October 2013 04:11:56 PM
Old 10-18-2013
Quote:
Originally Posted by CarloM
Some rough (and untested!) code:
Code:
tempfile=$(mktemp -t XXXXXXXX.$$) || exit 1

( tail -f file.txt |  awk '/get|point/ {gsub (/point.*/,"");print NF}' | tee "${tempfile}" ) &
tailpid=$!

while true
do
        sleep 1
        found=$(wc -l "${tempfile}"|awk '{print $1}')
        [ $found -gt 3 ] && break
done

rm "${tempfile}"
kill $tailpid

Quote:
Originally Posted by CarloM
One way to do it would be to run the tail/awk pipe in a background subshell, redirect that output to a temp file, and have the parent script terminate the subshell when the file is 3 lines long.
That is exactly what your code does, but killing the subshell leaves each process in the tail|awk|tee pipeline alive and orphaned.

On a more general note, I can't think of any reason to ever use the following pipeline to count the lines of a single file:
Code:
wc -l file |awk '{print $1}'

wc will not print a pathname if you redirect stdin, wc -l < file. Alternatively, you can use AWK alone and print NR from an END block.

Quote:
Originally Posted by Kibou
Here is the final version of the script. It works like a charm!
After running your script, you may want to consult with ps and, if necessary, rework your solution.

Regards,
Alister
This User Gave Thanks to alister For This Post:
CarloM
 

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