fatal: This operation must be run in a work tree<>
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You repository is bare, i.e. it does not have a working tree attached to it. You can clone it locally to create a working tree for it, or you could use one of several other options to tell Git where the working tree is, e.g. the --work-tree option for single commands, or the GIT_WORK_TREE environment variable. There is also the core.worktree configuration option but it will not work in a bare repository (check the man page for what it does).
# git --work-tree=/path/to/work/tree checkout master # GIT_WORK_TREE=/path/to/work/tree git status