Can not rebuild without flake after rebuild with flake

Help
1

before i use flake and everything seems fine if i run sudo nixos-rebuild switch --flake .#xxx, but now i can not run sudo nixos-rebuild switch, it raised error:

[ogios@nixos:/etc/nixos]$ sudo nixos-rebuild switch
error:
       … while evaluating the attribute 'config'

         at /nix/store/y45vqv6pa8bhgag1dw86rvi6rk55xhxn-source/lib/modules.nix:322:9:

          321|         options = checked options;
          322|         config = checked (removeAttrs config [ "_module" ]);
             |         ^
          323|         _module = checked (config._module);

       … while calling the 'seq' builtin

         at /nix/store/y45vqv6pa8bhgag1dw86rvi6rk55xhxn-source/lib/modules.nix:322:18:

          321|         options = checked options;
          322|         config = checked (removeAttrs config [ "_module" ]);
             |                  ^
          323|         _module = checked (config._module);

       (stack trace truncated; use '--show-trace' to show the full trace)

       error: file 'nixos-config' was not found in the Nix search path (add it using $NIX_PATH or -I)

       at «none»:0: (source not available)
building Nix...
error:
       … while evaluating the attribute 'config'

         at /nix/store/y45vqv6pa8bhgag1dw86rvi6rk55xhxn-source/lib/modules.nix:322:9:

          321|         options = checked options;
          322|         config = checked (removeAttrs config [ "_module" ]);
             |         ^
          323|         _module = checked (config._module);

       … while calling the 'seq' builtin

         at /nix/store/y45vqv6pa8bhgag1dw86rvi6rk55xhxn-source/lib/modules.nix:322:18:

          321|         options = checked options;
          322|         config = checked (removeAttrs config [ "_module" ]);
             |                  ^
          323|         _module = checked (config._module);

       (stack trace truncated; use '--show-trace' to show the full trace)

       error: file 'nixos-config' was not found in the Nix search path (add it using $NIX_PATH or -I)

       at «none»:0: (source not available)
building the system configuration...
error:
       … while evaluating the attribute 'config.system.build.toplevel'

         at /nix/store/y45vqv6pa8bhgag1dw86rvi6rk55xhxn-source/lib/modules.nix:322:9:

          321|         options = checked options;
          322|         config = checked (removeAttrs config [ "_module" ]);
             |         ^
          323|         _module = checked (config._module);

       … while calling the 'seq' builtin

         at /nix/store/y45vqv6pa8bhgag1dw86rvi6rk55xhxn-source/lib/modules.nix:322:18:

          321|         options = checked options;
          322|         config = checked (removeAttrs config [ "_module" ]);
             |                  ^
          323|         _module = checked (config._module);

       (stack trace truncated; use '--show-trace' to show the full trace)

       error: file 'nixos-config' was not found in the Nix search path (add it using $NIX_PATH or -I)

       at «none»:0: (source not available)

and echo $NIX_PATH returns nixpkgs=flake:nixpkgs:/nix/var/nix/profiles/per-user/root/channels

what should i do to remove flake usage and rebuild sucessfully

2

Something like this should work: sudo nixos-rebuild switch -I nixos-config=/etc/nixos/configuration.nix