When you run 'git hooks' with no arguments it will list all of the hooks installed on the system. It will run the hooks with the --about argument to generate the description that is shown. Checkout the hooks in contrib for some examples.
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-Debugging
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-When GIT_HOOKS_VERBOSE is set git-hooks will output each hook as it is run so you can trouble shoot hooks that don't report errors, but exit with non-zero.
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-GIT_HOOKS_VERBOSE=1 git commit