Add Change To That New Directory as a unix til

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

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+# 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)