git checkout branch from outside

Question

Problem: I need somehow to checkout an existing branch of a project that is already cloned locally on my file system without being in that particular folder of this project.

Answer 1

Since Git version 1.8.5, you can also use -C option. Be sure to use it before any other command:

git -C ~/my-git-repo checkout master

Note that it doesn't have to be specifically the .git folder. Here is the man documenation:

-C 
       Run as if git was started in  instead of the current 
       working directory. When multiple -C options are given, each
       subsequent non-absolute -C  is interpreted relative to
       the preceding -C .

       This option affects options that expect path name like --git-dir
       and --work-tree in that their interpretations of the path names
       would be made relative to the working directory caused by the -C option.
       For example the following invocations are equivalent:

           git --git-dir=a.git --work-tree=b -C c status
           git --git-dir=c/a.git --work-tree=c/b status