How To: Compare Two Files

Use the diff command to display line-by-line differences between two files. The general syntax of the diff command is:

diff FILE1 FILE2

The diff command will examine both FILE1 and FILE 2 and tell you what changes need to be made for FILE1 and FILE2 to match. Note that the diff command points to which lines need to be:

1. Added (a)
2. Deleted (d)
3. Changed (c)
4. Further lines in FILE1 identified with a less than (<) symbol and lines in FILE2 with a greater than (>) symbol.

Examples:

diff file1.txt file2.txt

Output:

2c2,3< URL: www.google.com---> URL: www.google.co.uk> Email: not@here.com

The contents of both files:

cat file1.txt

Output:

Welcome to Wherever You Are!URL: www.google.com

And 

cat file2.txt

Output:

Welcome to Wherever You Are!URL: www.google.co.ukEmail: not@here.com