[git] How to see the changes between two commits without commits in-between?

I wrote a script which displays diff between two commits, works well on Ubuntu.

https://gist.github.com/jacobabrahamb4/a60624d6274ece7a0bd2d141b53407bc

#!/usr/bin/env python
import sys, subprocess, os

TOOLS = ['bcompare', 'meld']

def getTool():
    for tool in TOOLS:
        try:
            out = subprocess.check_output(['which', tool]).strip()
            if tool in out:
                return tool
        except subprocess.CalledProcessError:
            pass
    return None

def printUsageAndExit():
    print 'Usage: python bdiff.py <project> <commit_one> <commit_two>'
    print 'Example: python bdiff.py <project> 0 1'
    print 'Example: python bdiff.py <project> fhejk7fe d78ewg9we'
    print 'Example: python bdiff.py <project> 0 d78ewg9we'
    sys.exit(0)

def getCommitIds(name, first, second):
    commit1 = None
    commit2 = None
    try:
        first_index = int(first) - 1
        second_index = int(second) - 1
        if int(first) < 0 or int(second) < 0:
            print "Cannot handle negative values: "
            sys.exit(0)
        logs = subprocess.check_output(['git', '-C', name, 'log', '--oneline', '--reverse']).split('\n')
        if first_index >= 0:
            commit1 = logs[first_index].split(' ')[0]
        if second_index >= 0:
            commit2 = logs[second_index].split(' ')[0]
    except ValueError:
        if first != '0':
            commit1 = first
        if second != '0':
            commit2 = second
    return commit1, commit2

def validateCommitIds(name, commit1, commit2):
    if commit1 == None and commit2 == None:
        print "Nothing to do, exit!"
        return False
    try:
        if commit1 != None:
            subprocess.check_output(['git', '-C', name, 'cat-file', '-t', commit1]).strip()
        if commit2 != None:
            subprocess.check_output(['git', '-C', name, 'cat-file', '-t', commit2]).strip()
    except subprocess.CalledProcessError:
        return False
    return True

def cleanup(commit1, commit2):
        subprocess.check_output(['rm', '-rf', '/tmp/'+(commit1 if commit1 != None else '0'), '/tmp/'+(commit2 if commit2 != None else '0')])

def checkoutCommit(name, commit):
    if commit != None:
        subprocess.check_output(['git', 'clone', name, '/tmp/'+commit])
        subprocess.check_output(['git', '-C', '/tmp/'+commit, 'checkout', commit])
    else:
        subprocess.check_output(['mkdir', '/tmp/0'])

def compare(tool, commit1, commit2):
        subprocess.check_output([tool, '/tmp/'+(commit1 if commit1 != None else '0'), '/tmp/'+(commit2 if commit2 != None else '0')])

if __name__=='__main__':
    tool = getTool()
    if tool == None:
        print "No GUI diff tools"
        sys.exit(0)
    if len(sys.argv) != 4:
        printUsageAndExit()

    name, first, second = None, 0, 0
    try:
        name, first, second = sys.argv[1], sys.argv[2], sys.argv[3]
    except IndexError:
        printUsageAndExit()

    commit1, commit2 = getCommitIds(name, first, second)

    if not validateCommitIds(name, commit1, commit2):
        sys.exit(0)

    cleanup(commit1, commit2)
    checkoutCommit(name, commit1)
    checkoutCommit(name, commit2)

    try:
        compare(tool, commit1, commit2)
    except KeyboardInterrupt:
        pass
    finally:
        cleanup(commit1, commit2)
    sys.exit(0)