Compare two lines in same file

Question

Given a file like the following:-

01/09/2005
02/09/2005
03/09/2006
03/09/2006

I wish to compare if the last two lines are the same, and return a 1 if so or a 0 if they are not.

I can get the last two using a cat tail -2

Answer 1

tail -n 2 filename.txt | uniq | wc -l

This will yield 1 for identical lines, 2 for different.

Answer 2

How about this:

lc=`wc -l filename.txt | cut -d " " -f1`
if [ $lc -ge 2 ]
then 
    ulc=`tail -n 2 filename.txt | uniq | wc -l`
    if [ $ulc -eq 1 ]
    then
        echo "Last two lines are identical"
    fi
fi

Answer 3

Try this

[ `cat | tail -n 2 | uniq | wc -l` -eq "1" ] && echo 1 || echo 0

Replace echo by exit to make it the exit value. Used echo just for quicker testing.

#!/bin/bash
[ `cat | tail -n 2 | uniq | wc -l` -eq "1" ] && exit 1
exit 0

Answer 4

This might work for you:

 sed -n '$!h;${G;/\(.*\)\n\1$/{s/.*/1/p;q};s/.*/0/p}' filename.txt