gistfile1.txt

#Get the current commit edits are based on
	-1) Obtain <ID> corresponding to tip of apporiate branch 'git rev-parse <branch>'.

#To obtain index file to record the edits to.
	0) Read the commit: 'GIT_INDEX_FILE=foo.index git read-tree <ID>'. Save the <ID> (obtained in step -1).


#Add
	#add file to git db from temp file or piped into hash-object -w --stdin

		1) Add the new contents to database 'git hash-object -w <temporary file containing end result of edit>'. This gives SHA-1.

	#stage the file
		2) Insert the file into index: 'GIT_INDEX_FILLE=foo.index git update-index --add --cacheinfo 100644 <ID-from-step-1> <path>'  
		(if there are multiple files to commit at once, repeat 1) and 2) for each.

#Commit
		
	3) Turn the index into tree: 'GIT_INDEX_FILE=foo.index git write-tree'. Out comes SHA-1.

 	4) Create commit: 'git commit-tree <ID-from-step-3> -p <id-from-step--1> <commit.msg' 
		(that is, commit message is passed in stdin!). You get yet another sha-1.

		GIT_{COMMITTER,AUTHOR}_{NAME,EMAIL}
> Invoke commit-tree with environment variable GIT_AUTHOR_NAME set to "Smith". How to do it is language-dependent.
<Ilari> In C it is via execve/execle.
<Ilari> (and execpe)



	5) Then update the branch: 'git update-ref refs/heads/branchname <id-from-step-4> <id-from-step--1>'. If this succeeds, you are done.