Move pages under tldr, lint run.sh, update docs

tldr/linux/update-alternatives

@@ -0,0 +1,29 @@
+---
+syntax: markdown
+tags: [tldr, linux]
+source: https://github.com/tldr-pages/tldr.git
+---
+# update-alternatives
+
+> A convenient tool for maintaining symbolic links to determine default commands.
+> More information: <https://manned.org/update-alternatives>.
+
+- Add a symbolic link:
+
+`sudo update-alternatives --install {{path/to/symlink}} {{command_name}} {{path/to/command_binary}} {{priority}}`
+
+- Configure a symbolic link for `java`:
+
+`sudo update-alternatives --config {{java}}`
+
+- Remove a symbolic link:
+
+`sudo update-alternatives --remove {{java}} {{/opt/java/jdk1.8.0_102/bin/java}}`
+
+- Display information about a specified command:
+
+`update-alternatives --display {{java}}`
+
+- Display all commands and their current selection:
+
+`update-alternatives --get-selections`