git replace local version with remote version

This is the safest solution:

git stash

Now you can do whatever you want without fear of conflicts.

For instance:

git checkout origin/master

If you want to include the remote changes in the master branch you can do:

git reset --hard origin/master

This will make you branch "master" to point to "origin/master".

I understand the question as this: you want to completely replace the contents of one file (or a selection) from upstream. You don't want to affect the index directly (so you would go through add + commit as usual).

Simply do

git checkout remote/branch -- a/file b/another/file

If you want to do this for extensive subtrees and instead wish to affect the index directly use

git read-tree remote/branch:subdir/

You can then (optionally) update your working copy by doing

git checkout-index -u --force

My understanding is that, for example, you wrongly saved a file you had updated for testing purposes only. Then, when you run "git status" the file appears as "Modified" and you say some bad words. You just want the old version back and continue to work normally.

In that scenario you can just run the following command:

git checkout -- path/filename

I would checkout the remote file from the "master" (the remote/origin repository) like this:

git checkout master <FileWithPath>

Example: git checkout master components/indexTest.html

Use the -s or --strategy option combined with the -X option. In your specific question, you want to keep all of the remote files and replace the local files of the same name.

Replace conflicts with the remote version

git merge -s recursive -Xtheirs upstream/master  

will use the remote repo version of all conflicting files.

Replace conflicts with the local version

git merge -s recursive -Xours upstream/master

will use the local repo version of all conflicting files.