How is the git hash calculated? : <p>I'm trying to understand how git calculates the hash of refs. </p>

<pre><code>$ git ls-remote https://github.com/git/git  

....
29932f3915935d773dc8d52c292cadd81c81071d    refs/tags/v2.4.2
9eabf5b536662000f79978c4d1b6e4eff5c8d785    refs/tags/v2.4.2^{}
....
</code></pre>

<p>Clone the repo locally. Check the <code>refs/tags/v2.4.2^{}</code> ref by sha</p>

<pre><code>$ git cat-file -p 9eabf5b536662000f79978c4d1b6e4eff5c8d785 

tree 655a20f99af32926cbf6d8fab092506ddd70e49c
parent df08eb357dd7f432c3dcbe0ef4b3212a38b4aeff
author Junio C Hamano &lt;gitster@pobox.com&gt; 1432673399 -0700
committer Junio C Hamano &lt;gitster@pobox.com&gt; 1432673399 -0700

Git 2.4.2

Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
</code></pre>

<p>Copy the decompressed content so that we can hash it.(AFAIK git uses the uncompressed version when it's hashing)</p>

<pre><code>git cat-file -p 9eabf5b536662000f79978c4d1b6e4eff5c8d785 &gt; fi
</code></pre>

<p>Let's SHA-1 the content using git's own hash command</p>

<pre><code>git hash-object fi
3cf741bbdbcdeed65e5371912742e854a035e665
</code></pre>

<p>Why the output is not <code>[9e]abf5b536662000f79978c4d1b6e4eff5c8d785</code>? I understand the first two characters (<code>9e</code>) is the length in hex. How should I hash the content of <code>fi</code> so that I can get the git ref <code>abf5b536662000f79978c4d1b6e4eff5c8d785</code> ?</p>
