Shell Programming and Scripting

Hello,

I have a single text file with three columns like:

Code:

2  1  10
3  6  11
4  4  12
5  5  13
6  8  14

I was wondering how I can run a shell script to (do loop) to read the first point in the first column , compare it with all the points in the second column and if they are the same, prints the relevant number in the third column? and it continues with the consecutive numbers in the first column.

so the output for the above set of data it would be:

Code:

4 12
5 13
6 11

Thank you,

Paul

You mean output like

Code:

4 12
5 13

??

Try:
awk '$1==$2{print $1" "$3}' input

Typically a rough main structure would be:

Code:

while read var1 var2 var3
do
  # do something with $var1 $var2 and $var3, for example
  echo "$var1, $var2 and $var3"
done < infile > outfile

Thanks for your response. It works absolutely fine. I changed further my question. what if I want to look for a match between my first data point in column 1 and the entire column 2?

Thanks again,

Paul

Could you please write output what you want to see?

Sure. I've added this to the initial question as well.

input

Code:

2  1  10
3  6  11
4  4  12
5  5  13
6  8  14

output

Code:

4 12
5 13
6 11

This can look backwards

Code:

awk '{seen[$2]=$3}
($1 in seen) {print $1,seen[$1]}' input