feat: add setup script to symlink git repository to /etc/nixos

setup

@@ -0,0 +1,24 @@
+#!/bin/sh
+
+# this file should be run after cloning this git repository
+# to set up nixos and versioning.
+
+BACKUP_SUFFIX=.bak-$(date +%Y%m%d-%H%M%S)
+
+# check if /etc/nixos exists or is a symlink
+if [ -L /etc/nixos ]; then
+  TARGET=$(readlink /etc/nixos)
+  sudo cp -r ${TARGET} /etc/nixos${BACKUP_SUFFIX}
+  sudo rm -rf /etc/nixos
+  echo "/etc/nixos has been backed up to /etc/nixos${BACKUP_SUFFIX}."
+elif [ -d /etc/nixos ]; then
+  sudo mv -v /etc/nixos /etc/nixos${BACKUP_SUFFIX} # back up the original config
+  echo "/etc/nixos has been backed up to /etc/nixos${BACKUP_SUFFIX}."
+else
+  echo "/etc/nixos does not exist. Backup not performed."
+fi
+
+SCRIPT_PATH=$(realpath "$0")
+DOTFILES_PATH=$(dirname ${SCRIPT_PATH})
+sudo ln -s ${DOTFILES_PATH} /etc/nixos
+echo "${DOTFILES_PATH} has been symlinked to /etc/nixos."