Add Change To That New Directory as a unix til

README.md

@@ -10,7 +10,7 @@ smart people at [Hashrocket](http://hashrocket.com/).
 For a steady stream of TILs from a variety of rocketeers, checkout
 [til.hashrocket.com](https://til.hashrocket.com/).
 
-_529 TILs and counting..._
+_530 TILs and counting..._
 
 ---
 
@@ -454,6 +454,7 @@ _529 TILs and counting..._
 - [All The Environment Variables](unix/all-the-environment-variables.md)
 - [Cat A File With Line Numbers](unix/cat-a-file-with-line-numbers.md)
 - [Change Default Shell For A User](unix/change-default-shell-for-a-user.md)
+- [Change To That New Directory](unix/change-to-that-new-directory.md)
 - [Check If A Port Is In Use](unix/check-if-a-port-is-in-use.md)
 - [Check The Current Working Directory](unix/check-the-current-working-directory.md)
 - [Clear The Screen](unix/clear-the-screen.md)

unix/change-to-that-new-directory.md

@@ -0,0 +1,31 @@
+# Change To That New Directory
+
+The `$_` variable provided by bash is always set to the last argument of the
+previous command. One handy use of this is for changing directories into a
+newly created directory.
+
+```bash
+$ mkdir new_dir && cd $_
+```
+
+This command will leave you in your newly created directory, `new_dir`.
+
+We can imagine using this bash variable in a number of similar scenarios as
+well. What if we are using some language specific command that creates a
+directory? Will it work with create a new Phoenix or Rails project?
+
+It sure will.
+
+Give it a try with Phoenix:
+
+```bash
+mix phx.new my_app && cd $_
+```
+
+or with Rails:
+
+```bash
+rails new app && cd $_
+```
+
+[source](http://tldp.org/LDP/Bash-Beginners-Guide/html/sect_03_02.html)