Shell Programming and Scripting

NAME
       diff3 - compare three files line by line

grep -f fileA fileB ;echo "----------"
grep -f fileA fileC;echo "----------"
grep -f fileA fileD;echo "----------"
grep -f fileB fileC;echo "----------"
grep -f fileB fileD;echo "----------"
grep -f fileC fileD;echo "----------"

#!/usr/bin/env bash

# @(#) s3	Demonstrate identification of common lines.
# Adapted from: radoulov
# https://www.unix.com/shell-programming-scripting/
# 140390-get-common-lines-multiple-files.html
# Post 8

pe() { for i;do printf "%s" "$i";done; printf "\n"; }
pl() { pe;pe "-----" ;pe "$*"; }

pl " Results of finding common lines with awk."
pe

awk 'END {
  for (R in rec) {
    n = split(rec[R], t, "/")
    if (n > 1) 
      dup[n] = dup[n] ? dup[n] RS sprintf("\t%-20s -->\t%s", rec[R], R) : \
        sprintf("\t%-20s -->\t%s", rec[R], R)
    }
  for (D in dup) {
    printf "records found in %d files:\n\n", D
    printf "%s\n\n", dup[D]
    }  
  }
{  
  rec[$0] = rec[$0] ? rec[$0] "/" FILENAME : FILENAME
  }' file?

exit 0

% ./s3

-----
 Results of finding common lines with awk.

records found in 2 files:

	file3/file4          -->	apple
	file1/file4          -->	neha

file?