diff --git a/bash/alias/bash.sh b/bash/alias/bash.sh
index 84b628d..65a7bda 100644
--- a/bash/alias/bash.sh
+++ b/bash/alias/bash.sh
@@ -1,6 +1,13 @@
 # change current directory to its parent
 alias ..="\
-cd .. \
+cd \
+.. \
+"
+
+# swap directory (current ↔ previous)
+alias sd="\
+cd \
+- \
 "
 
 # import source file