病情：
error@cox:/Users/mom$ brew update remote: Counting objects: 2482, done. remote: Compressing objects: 100% (750/750), done. remote: Total 2105 (delta 1543), reused 1822 (delta 1349) Receiving objects: 100% (2105/2105), 329.33 KiB | 122 KiB/s, done. Resolving deltas: 100% (1543/1543), completed with 295 local objects. From https://github.com/mxcl/homebrew f884112..28f7e01 master -> origin/master error: The following untracked working tree files would be overwritten by merge: Library/Formula/autojump.rb Please move or remove them before you can merge. Updating f884112..28f7e01 Aborting Error: Failed while executing git pull origin refs/heads/master:refs/remotes/origin/master
解决方法：
cd `brew --prefix` git clean -n # Does a dry run---shows what will get nuked without touching anything git clean -f # This will destroy files