index manipulation quickref

["Nguyen Thai Ngoc Duy" <pclouds@gmail.com>]

Hi,

I'm trying to collect all operations related to index from user
perspective and corresponding commands. The list may be put to git
wiki if people think it can help newbies:

update file content to index: git update-index file
add a file to index: git add file
delete a file from index: git update-index --remove --force-remove (or
remove that file in workdir and do git update-index --remove)
read a tree to index: git read-tree treeish, git reset treeish
read a file from a tree to index: git ls-tree treeish file|git
update-index --index-info --stdin
copy a file from index to workdir: git checkout-index file
refresh index: git update-index --refresh
copy entire index to workdir: git checkout-index
output a file from index to stdout: ?? (is there a command for this?)
list files in index: git ls-files
compare index and workdir file listing: git ls-files (with lots of options here)
diff between workdir and index: git diff
diff between index and a tree: git diff --cached treeish

Am I missing any operation here?
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