Shell Programming and Scripting

Sorry for this noob question,
I have file with 4 columns like where columns 2 and 4 have numbers

Code:

a 55  k 3
b 59 l 3
c 79 m 277
d 255 n 277
e 257 o 267
f 267 p 287
g 290  q 287
h 290 r 287
i 310 s 900

now i want to select only those rows, where values in column 4 are greater than those in column 2 in a range of 1 to 30.
so the out put should be like

Code:

m 277
n 277
o 267
p 287
q 287
r 287

and those which exactly have a difference of 10

Code:

m 277
n 277
o 267

I will appreciate any help. I hope this can be done with awk.
Thanks

I can't understand what you're trying to do. There are several problems here including:Please give us a clearer statement of your requirements and give us examples that match your requirements!

Hi Don, sorry for not being clear.
1. Sorry that was a sloppy way of showing sample data . It now has 4 columns

2. and 3. I need to compare all the rows of column 4 with all the rows of column 2, comparison is not limited to same rows. Which is why i printed 3rd row of column 3 and 4 because '277' in column 4 has a difference in range of 1-30 from values in column 2 in rows 4,5 etc.

Please do let me know if this question does not still make a clear sense.

Thank you.

Here is a simple brute force awk script that I think does what you want:

Code:

awk '
FNR == NR {
        for(i = ($2 + 1); i <= ($2 + 30); i++) r1to30[i]
        r10[$2 + 10]
        next
}
$4 in r10 {
        print $3, $4 > "out10"
}
$4 in r1to30 {
        print $3, $4 > "out1-30"
}' file file

It produces two output files: out10 contains columns 3 and 4 of the input file lines where column 4 is 10 greater than some value in column 2 of the input file, and out1-30 contains columns 3 and 4 of the input file lines where column 4 - some value in column 2 is greater than or equal to 1 and less than or equal to 30.