Cool. But for "index-newbies" not "git-newbies" :)
We could add (if exists) the porcelain-ish equivalent as:
update file content to index:
git update-index file
git add file (the development version)
add a file to index:
git update-index --add file
git add file
delete a file from index:
git update-index --remove [--force-remove] file
git rm file
read a tree to index:
git read-tree treeish
git reset commit-ish # It changes also the HEAD
read a file from a tree to index:
git ls-tree treeish file | git update-index --index-info --stdin
N/A
copy a file from index to workdir:
git checkout-index file
git checkout file
refresh index:
git update-index --refresh
git status # It does more things
copy entire index to workdir:
git checkout-index
git checkout -f
output a file from index to stdout:
git cat-file blob :file (or :n:file, where n=0,1,2,3 are the unmerged stage)
??
list files in index:
git ls-files
??
compare index and workdir file listing:
git ls-files (with lots of options here)
git status?
diff between workdir and index:
git diff-files
git diff
diff between index and a tree:
git diff-index --cached treeish
git diff --cached treeish