diffutils

Diffutils includes four utilities: diff, cmp, diff3 and sdiff.

• Diff compares two files and shows the differences, line by line.
• The cmp command shows the offset and line numbers where two files differ, or cmp can show the characters that differ between the two files.
• The diff3 command shows the differences between three files. Diff3 can be used when two people have made independent changes to a common original; diff3 can produce a merged file that contains both persons' changes and warnings about conflicts.
• The sdiff command can be used to merge two files interactively.

Install diffutils if you need to compare text files.