A very simple git pre-commit hook to add/set a VERSION file with each commit. It will automatically insert the version and add that to the pending commit. Note that git hooks are not distributed with the repo, though adding to a fresh repo via the dev environment bootstrap script for our project works fine.

output

~/work/tmp/version_file <master +>± git status
# On branch master
# Changes to be committed:
#   (use "git reset HEAD <file>..." to unstage)
#
#  new file:   foo
#
~/work/tmp/version_file <master +>± git diff --staged
diff --git a/foo b/foo
new file mode 100644
index 0000000..88bf918
--- /dev/null
+++ b/foo
@@ -0,0 +1 @@
+touched foo
~/work/tmp/version_file <master +>± git commit -m "touched ./foo"
[master 2e6a2d2] touched ./foo
 2 files changed, 2 insertions(+), 1 deletion(-)
 create mode 100644 foo
~/work/tmp/version_file <master>± git show
commit 2e6a2d2f13bb8c4ed321b90d8b591acf9116aecd
Author: Garrow Bedrossian <garrow.bedrossian@hitwise.com>
Date:   Tue Feb 26 14:06:43 2013 +1100

    touched ./foo

diff --git a/VERSION b/VERSION
index ec213cf..d0e6678 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-v0.1-1-g4584f85
+v0.1-2-g4fcc0c7
diff --git a/foo b/foo
new file mode 100644
index 0000000..88bf918
--- /dev/null
+++ b/foo
@@ -0,0 +1 @@
+touched foo

pre-commit

#!/bin/sh
# Filename is actually: .git/hooks/pre-commit
git describe > VERSION
git add VERSION