Linux / UNIX Display Lines Common in Two Files

Author: Vivek Gite Last updated: April 12, 2008 23 comments

Q. I’m trying to use diff command, but it is not working. I’d like to display those lines that are common to file1 and file2? How do I do it?

A. Use comm command; it compare two sorted files line by line. With no options, produce three column output. Column one contains lines unique to FILE1, column two contains lines unique to FILE2, and column three contains lines common to both files.

To Display Those Lines That Are Common to File1 and File2

Type the command as follows:
$ comm /path/to/file1/ /path/to/file2 $ comm -1 /path/to/file1/ /path/to/file2 $ comm -2 /path/to/file1/ /path/to/file2 $ comm -3 /path/to/file1/ /path/to/file2
Where,

-1 : suppress lines unique to FILE1
-2 : suppress lines unique to FILE2
-3 : suppress lines that appear in both files

You can also try out perl code (it was posted by someone at comp.unix.shell news group):

$ perl -ne 'print if ($seen{$_} .= @ARGV) =~ /10$/'  file1 file2

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23 comments… add one

Binny V A Apr 14, 2008 @ 19:37

And if you want to find the lines NOT common in 2 files, use diff

Reply Link
Aengus Oct 8, 2009 @ 1:42

I used the line of perl to find the common lines between two files, but I needed it to ignore case. The solution, provided by mu was:

perl -ne ‘print if ($seen{lc $_} .= @ARGV) =~ /10$/’ file1 file2

Thanks mu!

Aengus

Reply Link
- Setu Patel Jun 27, 2016 @ 8:18
  
  it does not work
  
  Reply Link
Anonymous Mar 17, 2010 @ 5:15

I am not able to find common lines between 2 files with comm -3.. I use diff instead:
Use regex of contents of the file instead of \d+

diff -y <(sort file1) out

And for finding lines that are present in file1 but not in file2:
diff –suppress-common-lines <(sort file1) ” > output

Reply Link
- Addie Oct 17, 2011 @ 21:34
  
  I don’t see where you specify file2 in either option. I’m interested in the second option.
  
  Reply Link
ryto Nov 19, 2010 @ 16:09

Why not:

comm -1 -2 /path/to/file1/ /path/to/file2

This works in the command line on OSX for showing on the common lines to the 2 files. (though perhaps it is limited to OSX’s flavor of BSD — haven’t tested elsewhere)

Reply Link
- jankes Jul 20, 2011 @ 10:39
  
  It works only for sorted files, so you need:
  /path/to/file1 | sort > /path/to/file1_sorted
  /path/to/file2 | sort > /path/to/file2_sorted
  comm -1 -2 /path/to/file1_sorted/ /path/to/file2_sorted
  
  Reply Link
  - ryto Jul 20, 2011 @ 14:04
    
    Ah, yes, good point. I was coming at it from two files of stats for which I had removed duplicate lines and sorted.
    
    Reply Link
dcl Dec 7, 2010 @ 2:07

Thanks for the Perl code. :-)
It works.

Reply Link
Amit Nag Nov 10, 2011 @ 7:16

This script takes two files as arguments $1 and $2 and prints common lines in the
two files.
===============================
while read line
do
echo “Searching for : ”
echo $line
while read lines
do
if [ “$lines” = “$line” ]
then
echo $line
fi
done < $2

done < $1
======================================
save this into a file then run it ./anyname file1 file2
NOTE : The input files must be intended i.e. no extra space in lines (i.e before or after lines.)

Reply Link
- tomi Nov 17, 2011 @ 21:55
  
  i tried it but it is not working
  
  Reply Link
  - Amit Nag Feb 14, 2012 @ 8:54
    
    ===============================
    while read line
    do
    echo “Searching for : ”
    echo $line
    while read lines
    do
    if [ “$lines” = “$line” ]
    then
    echo $line
    fi
    done < $2
    
    done < $1
    =============================================
    It works.
    anyname.sh — contains the above written script
    u have to change the privlges of the file to 777 :
    chmod 777 anyname.sh
    then run it :
    ./anyname.sh
    
    file1 and file2 can be any text files.
    
    Reply Link
    - Amit Nag Feb 14, 2012 @ 8:55
      
      U must run d script like dis only :
      wid arguments .
      ————————————-
      ./anyname.sh
      ————————————-
      
      Reply Link
      - Amit Nag Feb 14, 2012 @ 8:56
        
        U must run d script like dis only :
        wid arguments .
        ————————————-
        ./anyname.sh (file1) (file2)
        ————————————-
        
        Reply Link
Sunil Feb 10, 2012 @ 17:06

In Unix lets assume, I have 2 files .. file1 and file2
In file1
13
14
15
16
17
20
21
23
24
27
and in file2
16
17
18
24
25
30
32

Question : I would like to print the common strings(words) listed in file1 and file2 in the column wise only. i.e,
16
17
24

Reply Link
- narendra.a Dec 6, 2016 @ 12:43
  
  grep -f file1 file2
  will give the result as u expect
  
  Reply Link
Derek Oct 23, 2012 @ 2:09

paste the code below into a file called intersect.sh

while read line
do
grep -n “^${line}$” $2;
done < $1
then make sure you have execute permissions on the file

chmod 777 intersect.sh

then run this command, substituting the names of your two files

./intersect.sh nameOfLongerFile nameOfShorterFile

Reply Link
MP Apr 19, 2013 @ 21:47

Is there a quick way to get the matching lines plus (in one file) adjacent lines? The following works, but hits near the end of the files are incredibly inefficent:

while read p; do grep -A1 “$p” file2 ; done <file1

this'll match all lines from file1 in file2 (or at least the first match?) and provide the next line from file2 as well.

Reply Link
upendra Jun 9, 2013 @ 8:02

The perl one-liner worked very well for me. Thanks for providing that. Much appreciated.

Reply Link

Adrien Sep 23, 2013 @ 14:52

In python :

import sys,os
file1 = open(sys.argv[1],"r")
file2 = open(sys.argv[2],"r")

lines1 = file1.readlines()
lines2 = file2.readlines()
print "File %s has %s lines" % (sys.argv[1],len(lines1))
print "File %s has %s lines" % (sys.argv[2],len(lines2))

found = []
notfound = []
for idx,l in enumerate(lines1) :
	print "Doing line %s in file %s : %s" % (idx,sys.argv[1],l)
	for idx2,l2 in enumerate(lines2) :
		if l == l2 :
			print "Found %s ( ==  %s ) in file %s at index %s" % (l,l2, sys.argv[2],idx2)
			found.append(l)
			continue
			print "Found : %s , Not Found : %s" % (len(found),len(notfound))
	notfound.append(l)
	print "Found : %s , Not Found : %s" % (len(found),len(notfound))

python nameofthescript.py file1 file2

You can comment prints of course

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self Jan 28, 2015 @ 15:47

1) for i in `cat file1`; do grep –color $i file2; done
2) grep -f file1 file2

Reply Link
Arulraj Feb 2, 2015 @ 14:14

In a file having following data

adsdfsf 10 sdfd 10
sdsgfjf 5 hdvfd 10
gdyfdfd 20 jdfhd 564

I want to compare column one with column two. Please any body knows reply to my mail id.

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rod May 9, 2015 @ 17:46

i want to do this but with two strings saved in two bash variables… is this possible with comm?

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