git hash

GitSha1.java

import org.apache.commons.codec.digest.DigestUtils;


public class GitSha1 {

    public static String githash(String aString){
        return DigestUtils.sha1Hex("blob " + aString.length() + "\0" + aString);
    }

    public static void main(String[] args) {
        String theString = "this is the end, there is nothing else";
        String expected = "c9ee5714232648dfdaea316c8ae5a2549632e0bb";
        
        String result = githash(theString);

        System.out.println(result + " " + (result.equals(expected)?"correct":"incorrect"));
    }
}

gitsha1.py

from hashlib import sha1

def githash(data):
    s = sha1()
    s.update("blob %u\0" % len(data))
    s.update(data)
    return s.hexdigest()

# [klang@ergates aws-python]$ python -i sha1.py
# >>> githash("this is the end, there is nothing else")
# 'c9ee5714232648dfdaea316c8ae5a2549632e0bb'

gitsha1.sh

git_sha1 () { printf 'blob %s\0' "$(ls -l "$1" | awk '{print $5;}')" | cat - "$1" | sha1sum | awk '{print $1}'; }