---
name: "bsdiff"
section: "1"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["linux", "freebsd"]
url: "https://new.carta.tech/bsdiff"
---

# bsdiff(1)

generate a patch between two binary files

## NAME

**bsdiff** – generate a patch between two binary files

## SYNOPSIS

**bsdiff** *oldfile* *newfile* *patchfile*

## DESCRIPTION

The **bsdiff** utility compares *oldfile* to *newfile* and writes to *patchfile* a binary patch suitable for use by [bspatch(1)](/bspatch/1.md). When *oldfile* and *newfile* are two versions of an executable program, the patches produced are on average a factor of five smaller than those produced by any other binary patch tool known to the author.

The **bsdiff** utility uses memory equal to 17 times the size of *oldfile*, and requires an absolute minimum working set size of 8 times the size of *oldfile*.

## SEE ALSO

[bspatch(1)](/bspatch/1.md)

## AUTHORS

Colin Percival ⟨*cperciva@FreeBSD.org*⟩

## BUGS

The **bsdiff** utility does not store the hashes of *oldfile* or *newfile* in *patchfile*. As a result, it is possible to apply a patch to the wrong file; this will usually produce garbage. It is recommended that users of **bsdiff** store the hashes of *oldfile* and *newfile* and compare against them before and after applying *patchfile*.