Update cheatsheets

ex

@@ -0,0 +1,38 @@
+---
+syntax: markdown
+tags: [tldr, common]
+source: https://github.com/tldr-pages/tldr.git
+---
+# ex
+
+> Command-line text editor.
+> See also: `vim`.
+> More information: <https://www.vim.org>.
+
+- Open a file:
+
+`ex {{path/to/file}}`
+
+- Save and Quit:
+
+`wq<Enter>`
+
+- Undo the last operation:
+
+`undo<Enter>`
+
+- Search for a pattern in the file:
+
+`/{{search_pattern}}<Enter>`
+
+- Perform a regular expression substitution in the whole file:
+
+`%s/{{regular_expression}}/{{replacement}}/g<Enter>`
+
+- Insert text:
+
+`i<Enter>{{text}}<C-c>`
+
+- Switch to Vim:
+
+`visual<Enter>`