DCO automatic signoff git hook

prepare-commit-msg.md

https://stackoverflow.com/a/46536244/535610

Save the following as .git/hooks/prepare-commit-msg and make it executable.

#!/bin/sh

NAME=$(git config user.name)
EMAIL=$(git config user.email)

if [ -z "$NAME" ]; then
    echo "empty git config user.name"
    exit 1
fi

if [ -z "$EMAIL" ]; then
    echo "empty git config user.email"
    exit 1

fi

git interpret-trailers --if-exists doNothing --trailer \
    "Signed-off-by: $NAME <$EMAIL>" \
    --in-place "$1"