add tree

basics/tree.md

@@ -0,0 +1,25 @@
+---
+title: "tree"
+tags: [ "basics" ]
+---
+
+The `tree` utility outputs a full listing of everything in your current directory, and those below.
+
+- Just directories: `tree -d`
+- Output colour to `less`: `tree -C --info | less -re`
+- Ignore files in the `.gitignore` file: `tree --gitignore`
+
+You can place information about the files in a directory to use with the `tree --info` option, like this:
+
+```
+config
+	Config files.
+	This is a git submodule.
+README.md
+	Summary of the git.
+*.jpg
+	Little picture, does not display
+	words well.
+```
+
+Each description-line starts with a tab.