fixed titles, added notes and tips and added solutions to exercises

Author: lbarraga

mkdocs/docs/HPC/linux-tutorial/getting_started.md

@@ -1,23 +1,11 @@
-Getting Started
-===============
-
-Logging in
-----------
+# Getting Started
 
 To get started with the HPC-UGent infrastructure, you need to obtain a
-VSC account, see [HPC manual](../account.md).
-**Keep in mind that you must keep your private key to yourself!**
-
-You can look at your public/private key pair as a lock and a key: you
-give us the lock (your public key), we put it on the door, and then you
-can use your key to open the door and get access to the HPC
-infrastructure. **Anyone who has your key can use your VSC account!**
-
+VSC account, see [HPC manual](../account.md). 
 Details on connecting to the HPC infrastructure are available in
 [HPC manual connecting section](../connecting.md).
 
-Getting help
-------------
+## Getting help
 
 To get help:
 
@@ -42,8 +30,7 @@ carefully and try to act on it. Try googling the error first to find any
 possible solution, but if you can't come up with something in 15
 minutes, don't hesitate to mail <a href="mailto:{{hpcinfo}}">{{hpcinfo}}</a>.
 
-Basic terminal usage
---------------------
+## Basic terminal usage
 
 The basic interface is the so-called shell prompt, typically ending with
 `$` (for `bash` shells).
@@ -77,11 +64,11 @@ If for any reason you want to stop a command from executing, press
 `Ctrl-C`. For example, if a command is taking too long, or you want to
 rerun it with different arguments.
 
-Variables
----------
+## Variables
+
 [//]: # (sec:environment-variables())
 
-At the prompt we also have access to shell variables, which have both a
+At the prompt we also have access to *shell variables*, which have both a
 *name* and a *value*.
 
 They can be thought of as placeholders for things we need to remember.
@@ -95,8 +82,6 @@ shell variable named `HOME`:
 
 This prints the value of this variable.
 
-### Defining variables
-
 There are several variables already defined for you when you start your
 session, such as `$HOME` which contains the path to your home directory.
 
@@ -110,19 +95,27 @@ HOME=/user/home/gent/vsc400/vsc40000
 ...
 </code></pre>
 
+!!! info
+    In Linux, the pipe operator (`|`) is used to pass output from one command as input to another. 
+    This is known as a pipeline. Here, `env | sort` will take the output of `env` and use it as the input for `sort`. 
+    This can be extremely useful for chaining together commands and processing data.
+
 You can also use the `grep` command to search for a piece of text. The
 following command will output all VSC-specific variable names and their
 values:
 
 <pre><code>$ <b>env | sort | grep VSC</b></code></pre>
 
-But we can also define our own. this is done with the `export` command
-(note: variables are always all-caps as a convention):
+### Defining variables
+
+It is also possible to define your own variables. this is done with the `export` command:
 
 <pre><code>$ <b>export MYVARIABLE="value"</b></code></pre>
 
-It is important you don't include spaces around the `=` sign. Also note
-the lack of `$` sign in front of the variable name.
+
+!!! note
+    Notice the lack of the `$` sign and spaces around the `=` sign. 
+    By convention, variables should be all-caps.
 
 If we then do
 <pre><code>$ <b>echo $MYVARIABLE</b></code></pre>
@@ -131,56 +124,11 @@ this will output `value`. Note that the quotes are not included, they
 were only used when defining the variable to escape potential spaces in
 the value.
 
-#### Changing your prompt using `$PS1`
-
-You can change what your prompt looks like by redefining the
-special-purpose variable `$PS1`.
-
-For example: to include the current location in your prompt:
-<pre><code>$ <b>export PS1='\w $'</b>
-~ $ cd test
-~/test $
-</code></pre>
-
-Note that `~` is short representation of your home directory.
-
-To make this persistent across session, you can define this custom value
-for `$PS1` in your `.profile` startup script:
-<pre><code>$ <b>echo 'export PS1="\w $ " ' >> ~/.profile</b></code></pre>
-
-### Using non-defined variables
-
-One common pitfall is the (accidental) use of non-defined variables.
-Contrary to what you may expect, this does *not* result in error
-messages, but the variable is considered to be *empty* instead.
-
-This may lead to surprising results, for example:
-<pre><code>$ <b>export WORKDIR=/tmp/test</b>
-$ <b>pwd</b>
-/user/home/gent/vsc400/vsc40000
-$ <b>echo $HOME</b>
-/user/home/gent/vsc400/vsc40000
-</code></pre>
-
-To understand what's going on here, see the section on `cd` below.
-
-The moral here is: **be very careful to not use empty variables unintentionally**.
-
-**Tip for job scripts: use `set -e -u` to avoid using empty variables accidentally.**
-
-The `-e` option will result in the script getting stopped if any command
-fails.
-
-The `-u` option will result in the script getting stopped if empty
-variables are used. (see <https://ss64.com/bash/set.html> for a more
-detailed explanation and more options)
-
-More information can be found at <http://www.tldp.org/LDP/abs/html/variables.html>.
 
 ### Restoring your default environment
 
 If you've made a mess of your environment, you shouldn't waste too much
-time trying to fix it. Just log out and log in again and you will be
+time trying to fix it. Just log out and log in again, and you will be
 given a pristine environment.
 
 Basic system information
@@ -205,20 +153,49 @@ Linux gligar01.gligar.os 2.6.32-573.8.1.el6.ug.x86_64 #1 SMP Mon Nov 16 15:12:09
 
 
 
-Exercises
----------
+## Exercises
 
--   Print the full path to your home directory
+??? abstract "Print the full path to your home directory"
+    ```bash
+    $ echo $HOME
+    ```
 
--   Determine the name of the environment variable to your personal
-    scratch directory
+??? abstract "Determine the name of the environment variable to your personal scratch directory"
+    ```bash
+    $ env | grep SCRATCH
+    ```
 
--   What's the name of the system you're logged into? Is it the same for
-    everyone?
+??? abstract "What's the name of the system you're logged into? Is it the same for everyone?"
+    ```bash
+    $ hostname
+    ```
+    
+    Not everyone will be logged in to the same node, so the output will differ.
+
+??? abstract "Figure out how to print the value of a variable without including a newline"
+    
+    We can use the `man` command to find relevant information on the echo command with:
 
--   Figure out how to print the value of a variable without including a
-    newline
+    ```bash
+    $ man echo
+    ```
 
--   How do you get help on using the `man` command?
+    We find the following line in the manual:
+
+    ```
+    -n     do not output the trailing newline
+    ```
+    
+    So we can use the `-n` flag to suppress the newline:
+    
+    ```bash
+    $ echo -n $HOME
+    ```
+
+??? abstract "How do you get help on using the `man` command?"
+    
+    ```bash
+    $ man man
+    ```
 
-Next [chapter](navigating.md) teaches you on how to navigate.
+Next [chapter](navigating.md) teaches you how to navigate the filesystem.