How to compare 2 files line by line with terminal

Question

I have 2 text files that I need to compare line by line.

I'm basically wanting to output either "matching" or "not matching" for each line depending on if it matches.

I've tried reading a few tutorial and using stuff like diff and dircmp but can't seem to find a way to do this. I don't care if it's bash, perl, python, etc. Both files are 243 lines.

Is there a command available in Linux to do this?

Here's an example of what I'm looking for...

File 1

Test
Hello
Example

File 2

Test
What
Example

And I'd want to output this:

matching
not matching
matching

If you search in your browser for "Linux file match", you'll find references that can explain this much better than we can manage here. There are more on match file names than file contents, but you'll get the 'diff' family and examples. "Can't seem to find a way" is not generally a Stack Overflow question. What did you try that failed? For instance, `diff` is pretty straightforward: if it finds any difference, you report "not matching". — Prune, Jul 17 '19 at 16:11
Related, but not a duplicate: https://stackoverflow.com/q/4544709/8344060 — kvantour, Jul 17 '19 at 16:19
Not the requested output, but `diff -y File1 File2` or `sdiff File1 File2` might be useful. — Bodo, Jul 17 '19 at 16:51

score 1 · Answer 1 · answered Jul 17 '19 at 18:11

In perl:

#!/usr/bin/perl

use strict;
use File::Slurp;

my @file1 = read_file 'file1', { chomp => 1 };
my @file2 = read_file 'file2', { chomp => 1 };

foreach (@file1) {
  my $line = shift @file2;
  print $_ eq $line ? "not matching\n" : "matching\n";
}

score 0 · Accepted Answer · answered Jul 17 '19 at 16:23

What you are after is an awk script of the following form:

$ awk '(NR==FNR){a[FNR]=$0;next}
       !(FNR in a) { print "file2 has more lines than file1"; exit 1 }
       { print (($0 == a[FNR]) ? "matching" : "not matching") }
       END { if (NR-FNR > FNR) print "file1 has more lines than file2"; exit 1}' file1 file2

score 0 · Answer 3 · answered Jul 17 '19 at 17:49

This script works on the basis that both of your files are 243 lines. You will need to sort both files before running the script ie sort file1.txt > file1.sorted.txt and the same for the other file.

#!/bin/bash
while read file1 <&3 && read file2 <&4
  if [[ $file1 == $file2 ]]; then
    echo "matching" >> three.txt
  else
    echo "not matching" >> three.txt
  fi
done 3</path/to/file1.sorted.txt 4</path/to/file2.sorted.txt

The above script will read each file line by line, comparing the input using the if statement. If the two strings are identical, it will write "matching" to three.txt else it will write "not matching" to the same file. The loop will go through each line.

You will have to sort the data within both files to make a comparison. I've tested it with the following data:

one.sorted.txt

abc
cba
efg
gfe
xyz
zxy

two.sorted.txt

abc
cbd
efh
gfe
xyz
zmo

three.txt

matching
not matching
not matching
matching
matching
not matching

NSegal · Answer 4 · 2022-01-03T09:58:05.763

Its best to use dedicated linux file comparing tools such as Meld or Vimdiff, they are pretty straight forward and very convinient.

You can enter 'which meld' to check if you have it installed, if not found, install using this:

sudo apt-get install meld

In addition, here is a simple python script to get the results you asked for:

#!/usr/bin/env python3


with open ('1.txt') as f1:
    lines1 = f1.readlines()
    lines1 = [line.rstrip() for line in lines1]
with open ('2.txt') as f2:
    lines2 = f2.readlines()
    lines2 = [line.rstrip() for line in lines2]

for i, line in enumerate(range(min(len(lines1),len(lines2)))):
    print("matching") if lines1[i] == lines2[i] else print("not matching")

How to compare 2 files line by line with terminal

4 Answers4