Split update alternative

Author: cirosantilli

desktop/README.md

@@ -1530,6 +1530,8 @@ This talks about how to allow users to choose their default application when ope
 
 There are many systems, and they have some degree of compatibility.
 
+`update-alternatives` and `/etc/alternatives` is an important Linux method of executable selection.
+
 ### xdg-open
 
 XDG utils package, part of the LSB.
@@ -1569,37 +1571,6 @@ Gnome specific. Use `xdg-open` instead..
 
 KDE specific. Use `xdg-open` instead..
 
-### alternatives system
-
-One configuration method is to make symbolic links such as `/usr/bin/editor` to either `vi` or `ed` for example.
-
-The standard way is to first link `/usr/bin/editor` to `/etc/alternatives/editor`, and then `/etc/alternatives/editor` to the desired executable (say `/usr/bin/vi`).
-
-In this way, all preferences are stored under `etc` as specified by the LSB.
-
-### update-alternatives
-
-The `update-alternatives` utility can be used to manage that system.
-
-For example, to configure the default browser use:
-
-    sudo update-alternatives --config x-www-browser
-
-This will show the possibilities (TODO how does he know?) for you to choose from them.
-
-The most important alternatives include:
-
-- `editor`: text editor
-- `x-www-browser`: web browser
-
-TODO: understand the following command:
-
-    sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.8 50
-
-- `50`: priority of the alternative. Metadata associated by `update-alternatives`. Alternative with greatest priority wins.
-
-I used this to link `gcc` to `gcc-4.8` instead of `4.6`.
-
 ## logkeys
 
 Writes all key presses to a file.

desktop/update-alternatives.md

@@ -0,0 +1,48 @@
+# update-alternatives
+
+# /etc/alternatives
+
+Utility that manages which version of executables is going to be run through symlinks.
+
+For example Ubuntu 14.04 comes with
+
+    which editor
+
+as `/usr/bin/editor`, and:
+
+    readlink `which editor`
+
+Gives:
+
+    /etc/alternatives/editor
+
+And:
+
+    readlink /etc/alternatives/editor
+
+Points to:
+
+    /usr/bin/vi
+
+In this way, all preferences are stored under `etc` as specified by the LSB.
+
+The `update-alternatives` utility can be used to manage that system.
+
+For example, to configure the default browser use:
+
+    sudo update-alternatives --config x-www-browser
+
+This will show the possibilities (TODO how does he know?) for you to choose from them.
+
+Important alternatives include:
+
+- `editor`: text editor
+- `x-www-browser`: web browser
+
+TODO: understand the following command:
+
+    sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.8 50
+
+- `50`: priority of the alternative. Metadata associated by `update-alternatives`. Alternative with greatest priority wins.
+
+I used this to link `gcc` to `gcc-4.8` instead of `4.6`.

linux.md

@@ -155,6 +155,10 @@ Original installation file.
 
 Many theories, a plausible one: differentiate `a.conf file` from `a.conf.d` dir normally, all files in the `a.conf.d` dir will be sourced as if they are inside `a.conf`.
 
+#### /etc/environment
+
+TODO
+
 ## Distributions
 
 A Linux distribution is a LSB compliant system.