When Magit calls Git, then it may do so using the absolute path to the
git executable, or using just its name.
When running git locally and the system-type is windows-nt (any
Windows version) or darwin (macOS) then magit-git-executable is set
to an absolute path when Magit is loaded.
On Windows it is necessary to use an absolute path because Git comes
with several wrapper scripts for the actual git binary, which are also
placed on $PATH, and using one of these wrappers instead of the binary
would degrade performance horribly. For some macOS users using just
the name of the executable also performs horribly, so we avoid doing
that on that platform as well. On other platforms, using just the
name seems to work just fine.
Using an absolute path when running git on a remote machine over
Tramp, would be problematic to use an absolute path that is suitable
on the local machine, so a separate option is used to control the name
or path that is used on remote machines.
The git executable used by Magit on the local host. This should be
either the absolute path to the executable, or the string "git" to
let Emacs find the executable itself, using the standard mechanism
for doing such things.
The git executable used by Magit on remote machines over Tramp.
Normally this should be just the string "git". Consider customizing
tramp-remote-path instead of this option.
If Emacs is unable to find the correct executable, then you can
work around that by explicitly setting the value of one of these two
options. Doing that should be considered a kludge; it is better to
make sure that the order in exec-path or tramp-remote-path is correct.
Note that exec-path is set based on the value of the PATH environment
variable that is in effect when Emacs is started. If you set PATH in
your shell’s init files, then that only has an effect on Emacs if you
start it from that shell (because the environment of a process is only
passed to its child processes, not to arbitrary other processes). If
that is not how you start Emacs, then the exec-path-from-shell package
can help; though honestly I consider that a kludge too.
The command magit-debug-git-executable can be useful to find out where
Emacs is searching for git.
This command displays a buffer with information about
magit-git-executable and magit-remote-git-executable.
This command shows the currently used versions of Magit, Git, and Emacs in the echo area. Non-interactively this just returns the Magit version.