diff --git a/shell/alias/shell.sh b/shell/alias/shell.sh
index 9c9e8e7..d6aa697 100644
--- a/shell/alias/shell.sh
+++ b/shell/alias/shell.sh
@@ -1,32 +1,27 @@
-# change current directory to its parent
-alias ..="\
-cd \
-.. \
-"
-
-# change current directory to its parent’s parent
-alias ...="\
-cd \
-../.. \
-"
-
 # shorten alias
-alias a="\
-alias \
-"
+a() {
+	alias \
+		"${@}"
+}
 
 # swap directory (current ↔ previous)
-alias sd="\
-cd \
-- \
-"
-
-# import source file
-alias src="\
-. \
-"
+sd() {
+	cd - || return
+}
 
 # exit terminal
-alias x="\
-exit \
-"
+x() {
+	exit \
+		"${@}"
+}
+
+# back
+
+# shellcheck disable=SC3033
+..() {
+	cd ..
+}
+# shellcheck disable=SC3033
+...() {
+	cd ../..
+}