Diff to get changed line from second file

Question

I have two files file1 and file2. I want to print the new line added to file2 using diff.
file1

/root/a
/root/b
/root/c
/root/d

file2

/root/new
/root/new_new
/root/a
/root/b
/root/c
/root/d

Expected output

/root/new
/root/new_new

I looked into man page but there was no any info on this

Duplicate of https://stackoverflow.com/questions/15384818/how-to-get-the-difference-only-additions-between-two-files-in-linux . — Jordan Samuels, Mar 29 '18 at 14:08
@Jordan Samuels As someone already commented in that other question, it will leave you with a + at the beginning of the line. — pcjr, Mar 29 '18 at 15:16

score 2 · Accepted Answer · answered Mar 29 '18 at 14:07

2

If you don't need to preserve the order, you could use the comm command like:

comm -13 <(sort file1) <(sort file2)

comm compares 2 sorted files and will print 3 columns of output. First is the lines unique to file1, then lines unique to file2 then lines common to both. You can supress any columns, so we turn of 1 and 3 in this example with -13 so we will see only lines unique to the second file.

or you could use grep:

grep -wvFf file1 file2

Here we use -f to have grep get its patterns from file1. We then tell it to treat them as fixed strings with -F instead of as patterns, match whole words with -w, and print only lines with no matches with -v

answered Mar 29 '18 at 14:07

Eric Renouf

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As I needed to maintain the order so i used the `grep -wvFf file1 file2` but there was no output. Ain't it supposed to print the added line? – Dsujan Mar 29 '18 at 14:59
@SujanDulal one thing I noticed from your sample input is one of them has carriage returns and the other doesn't. If possible you might want to run `dos2unix` on both files so you get rid of those different line endings (otherwise they will be treated as part of the match) – Eric Renouf Mar 29 '18 at 15:02
I actually jumbled the file during input that was the problem. Thank you for the suggestion. I will filter out the carriage return. – Dsujan Mar 29 '18 at 15:10

score 1 · Answer 2 · answered Mar 29 '18 at 14:02

1

Following awk may help you on same. This will tell you all those lines which are present in Input_file2 and not in Input_file1.

awk 'FNR==NR{a[$0];next} !($0 in a)'  Input_file1  Input_file2

answered Mar 29 '18 at 14:02

RavinderSingh13

130,504
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score 1 · Answer 3 · answered Mar 29 '18 at 15:12

Try using a combination of diff and sed.

The raw diff output is:

$ diff file1 file2
0a1,2
> /root/new
> /root/new_new

Add sed to strip out everything but the lines beginning with ">":

$ diff file1 file2 | sed -n -e 's/^> //p'
/root/new
/root/new_new

This preserves the order. Note that it also assumes you are only adding lines to the second file.

Diff to get changed line from second file

3 Answers3