fix shell script and make checks target

justfile

@@ -1,21 +1,23 @@
 _default:
     @just --list
 
+# runs checks
+checks: _shellcheck _shfmt
+
+_shellcheck:
+    shellcheck *.sh
+
+_shfmt:
+    shfmt -i 2 -w -s *.sh
+
 # performs steps for mac
 mac:
     ./install-cli-tools.sh
-    ./setup-shell-config.sh
+    [ -f "$HOME/.nix-profile/bin/terminal-notifier" ] || nix profile install nixpkgs#terminal-notifier
+    ./setup-shell-configs.sh
     ./install-mac-apps.sh
 
 # performs steps for linux
 linux:
     ./install-cli-tools.sh
-    ./setup-shell-config.sh
+    ./setup-shell-configs.sh
-
-# checks all shell scripts for errors
-shellcheck:
-    shellcheck *.sh
-
-# formats all shell scripts consistently
-shfmt:
-    shfmt -i 2 -w -s *.sh