fix: keep the existing '.zshrc' file in the same directory

[wintermi]

The current version moves the existing .zshrc file to the $HOME directory even when the $ZDOTDIR is populated.

This fix will keep the existing .zshrc file in the same location as specified by the $ZDOTDIR

[mamaraddio]

NEW_ZSHRC could become:

local _ZSHRCBACKUP="${ZSHRC}_$(date +%Y-%m-%d)_$(date +%s)"

DATE ad ID could so be deleted, and finally:

mv "$ZSHRC" "$_ZSHRCBACKUP"

What do you think?

[wintermi]

I agree that the DATE and ID could be removed, though I wanted to fix the issue before refactoring anything further.