How to display only different rows using diff (bash)

Question

How can I display only different rows using diff in a separate file?

For example, the file number 1 contains the line:

1;john;125;3
1;tom;56;2
2;jack;10;5

A file number 2 contains the following lines:

1;john;125;3
1;tom;58;2
2;jack;10;5

How to make in the following happen?

1;tom;58;2

Answer 1

I found the following the easiest to visualise and understand, showing each file's unique lines side by side:

diff -y --suppress-common-lines "file1" "file2"

Answer 2

The following command provides only differences of two files one line at a time :

diff -W 400 -ay --suppress-common-lines <(nl file1) <(nl file2) | sed 's/|'"$(printf '\t')"'\+ \+/\n/g' | sed 's/^'"$(printf '\t')"'* */\n/g' | grep -aE '[0-9]'

It displayed the location of the difference and juste the lines which are different. the -W 400 should be adjusted to the max length of line of both files. The -a is not mandatory but it is really useful in case of text files which are recognized as binary by the system.

Answer 3

Here's a simple solution that I think is better than diff:

sort file1 file2 | uniq -u

• sort file1 file2 concatenates the two files and sorts it
• uniq -u prints the unique lines (that do not repeat). It requires the input to be pre-sorted.

Answer 4

Using group format specifiers you can suppress printing of unchanged lines and print only changed lines for changed

diff --changed-group-format="%>" --unchanged-group-format="" file1 file2

Answer 5

a.txt:

1;john;125;3
1;tom;56;2
2;jack;10;5

b.txt:

1;john;125;3
1;tom;58;2
2;jack;10;5

Use comm:

comm -13 a.txt b.txt 
1;tom;58;2

The command line options to comm are pretty straight-forward:

-1 suppress column 1 (lines unique to FILE1)

-2 suppress column 2 (lines unique to FILE2)

-3 suppress column 3 (lines that appear in both files)

Answer 6

Assuming you want to retain only the lines unique to file 2 you can do:

comm -13 file1 file2

Note that the comm command expects the two files to be in sorted order.