Consider the following cases:

• The original file foo is not needed anymore but its content should continue to be used in N new files (e.g. bar and baz):

  • First commit:
    • Duplicate the content without any changes: cp foo bar, cp foo baz
    • Add the new files, remove the old file: git add bar bar, git rm foo
  • Following commits:
    • Apply arbitrary changes to the new files and still be able to see the full history:
      • Blame bar
      • Blame baz
  • 👍

• The original file foo is still needed but parts of the content should be copied / moved to a new file (e.g. bar):

  • First commit:

    • Duplicate the content without any changes: cp foo bar
    • Add the new file: git add bar

  • Following commits:

    • Apply arbitrary changes to the new file but you can't see the full history anymore:
      • Blame bar

  • 👎

  • First commit:

    • Duplicate the content without any changes: cp foo dummy
    • Add the new dummy file, remove the old file: git add dummy, git rm foo

  • Apply the first option:

    • Duplicate the content without any changes: cp dummy foo, cp dummy bar
    • Add the new files, remove the old dummy file: git add foo bar, git rm dummy

  • Following commits:

    • Apply arbitrary changes to the new files and still be able to see the full history:
      • Blame foo
      • Blame bar

  • 👍