I've done 'git pull', and received a merge conflict. I know that the other version of the file is good, and that mine is bad (all my changes should be abandoned). How do I do this?
unmerged: _widget.html.erb
You are in the middle of a conflicted merge.
git checkout _widget.html.erb
this will replace the local version of the file with the version from repository.
I think it's git reset you need.
Beware that git revert means something very different to, say, svn revert - in Subversion the revert will discard your (uncommitted) changes, returning the file to the current version from the repo, whereas git revert "undoes" a commit.
git reset should do the equivalent of svn revert, i.e. discard your unwanted changes.
Since your pull was unsuccessful then just HEAD is the last "valid" commit on your branch (not HEAD^):
git reset --hard HEAD
The other piece you want is to let their changes over-ride your changes.
Older versions of git allowed you to use the "theirs" merge strategy:
git pull --strategy=theirs remote_branch
But this has since been removed, as explained in this message by Junio Hamano (the Git maintainer). As noted in the link, instead you would do this:
git fetch origin
git reset --hard origin
In this particular use case, you don't really want to abort the merge, just resolve the conflict in a particular way.
There is no particular need to reset and perform a merge with a different strategy, either. The conflicts have been correctly highlighted by git and the requirement to accept the other sides changes is only for this one file.
For an unmerged file in a conflict git makes available the common base, local and remote versions of the file in the index. (This is where they are read from for use in a 3-way diff tool by git mergetool.) You can use git show to view them.
# common base:
git show :1:_widget.html.erb
# 'ours'
git show :2:_widget.html.erb
# 'theirs'
git show :3:_widget.html.erb
The simplest way to resolve the conflict to use the remote version verbatim is:
git show :3:_widget.html.erb >_widget.html.erb
git add _widget.html.erb
Or, with git >= 1.6.1:
git checkout --theirs _widget.html.erb
An alternative, which preserves the state of the working copy is:
git stash
git merge --abort
git stash pop
I generally advise against this, because it is effectively like merging in Subversion as it throws away the branch relationships in the following commit.
Since Git 1.6.1.3 git checkout has been able to checkout from either side of a merge:
git checkout --theirs _widget.html.erb
http://www.kernel.org/pub/software/scm/git/docs/git-checkout.html