Three-Way Comparison With diff3

See how two edited files differ from their common base.

LinuxdiffgitLow risk

Run diff3 mine.txt base.txt yours.txt to list conflicting and overlapping regions.

01Command

Command

$ diff3 mine.txt base.txt yours.txt

02What it does

diff3 is the algorithm behind merge conflicts: it compares two versions against their ancestor and marks exactly what conflicts. Running it manually helps understand a conflicted merge and confirms that an automated resolution kept the right changes.

03Risk

RiskLow risk

Requirementssudo apt install diffutils

!Warning: The argument order is important (mine, base, yours); reversing base and a side produces misleading output.

04Undo

✓No undo needed — this command does not change persistent state.

05Sources

diff3.1.en.html manual page (Debian bookworm)
Debian · technical · 2026-09-20
Evidence: Documents diff3, which compares three files and marks conflicts.

Last verified: 2026-10-13 · Category: Developer

06Related solutions

Create and Apply Patches with diff -u and patch

Linuxdiffpatchtext

Generate a unified diff between two files, apply it to another copy with patch, and reverse it with patch -R.

Low risk ✓ 2026-09-17