Code

I wrote this script recently for a friend in a job who needed to output a certain percentage of a log file, but no more and no less. This was in Linux using bash, so I had a go at writing a solution, which you see below. Posting this up in case it’s useful to anyone else! # !/bin/sh # Public Domain, by Neil Grogan 2010 # Script to output last 30% of file by lines OLDFILE="oldlog.txt" NEWFILE="newlog.txt" PERCENT=0.7 #Use wc to count lines LINES=$(wc -l $OLDFILE | awk '{ print $1}') #Linespercent = 2 decimal places, lines by percent, round to whole LINESPERCENT=$(echo "scale=2; $LINES*$PERCENT" | bc | xargs printf "%1.0f" ) # Use tail to get last 30% and output, can use tail -s with sleep time to have it run on sched. tail -n $LINESPERCENT $OLDFILE >> $NEWFILE