Update "command line" lecture

The only problem with this lecture that I can remember is the general problem with Windows users

We could either try to get our hands on a Windows machine before the lecture and try to come up with a recommendation on how to connect to Levante, or hope that no Windows users will show up

lectures/command-line/slides.qmd

 ---
 title: "The command line"
 subtitle: "Controlling local and remote machines"
-author: "Lukas Kluft and Florian Ziemen"
 ---
 
 # Shell
 
 * A shell exposes an operating system to a human user or other programs
-* On most Linux systems the default shell is _Bash_ (_PowerShell_ on Windows; _Zsh_ on MacOs)
+* On most Linux systems, the default shell is _Bash_ (_PowerShell_ on Windows; _Zsh_ on MacOs)
 * Different shells come with different syntax and characteristics
 
 ## Built-in commands
@@ -32,7 +31,7 @@ author: "Lukas Kluft and Florian Ziemen"
   ```{.sh}
   vim test.txt
   ```
-* Basic usage: hit {{< kbd i >}} to activate _insert_ mode. Type something and hit {{< kbd Esc >}} to fall back into _normal_ mode. Save and close the file using {{< kbd :wq >}}.
+* Basic `vim` usage: hit {{< kbd i >}} to activate _insert_ mode. Type something and hit {{< kbd Esc >}} to fall back into _normal_ mode. Save and close the file using {{< kbd :wq >}}.
 
 ## Scripts
 
@@ -53,13 +52,13 @@ author: "Lukas Kluft and Florian Ziemen"
 
 ## Take home messages
 
-* The command line is a text interface to interact with a computer
+* The command line is a text interface for interacting with a computer
 * Built-in commands and core utilities are available on (almost) all machines
 * Sequences of commands can be stored and executed as shell scripts
 
 # Hands-on session {.handson}
 
-1. Open the command line (_Terminal_)
+1. Open the command line (_Terminal_^[More difficult for Windows users])
 1. Create a shell script using an editor of your choice
 1. Run the script and check the output
 
@@ -68,16 +67,7 @@ author: "Lukas Kluft and Florian Ziemen"
 
 ## Configuration
 
-::: {.r-stack}
-::: {.fragment .fade-out fragment-index=1}
-Supercomputers consist of various components
-:::
-::: {.fragment .fade-in fragment-index=1}
 High-performance computers consist of various components
-:::
-:::
-
-. . .
 
 :::: {.columns}
 
@@ -99,7 +89,8 @@ High-performance computers consist of various components
 Different ways to work on a cluster depending on the task:
 
 * Housekeeping/compiling (login nodes)
-* Interactive sessions/scripts on a compute node (`salloc`/`sbatch`)
+* Interactive sessions (compute nodes, `salloc`)
+* Batch scripts (compute nodes, `sbatch`)
 * External services (e.g. _Jupyterhub_)
 
 ## SSH
@@ -108,8 +99,7 @@ Different ways to work on a cluster depending on the task:
   ```{raw}
   ssh <YOUR_USERNAME>@levante.dkrz.de
   ```
-  (use your user id instead of a123456)
-* Now you have access to the command line on levante
+* Now you have access to the command line **on levante**
 
 ## Public keys
 
@@ -117,12 +107,12 @@ Different ways to work on a cluster depending on the task:
 
 ## Generating SSH keys
 
-* Generate a private / public ssh key pair for authentication on your local system
+* Generate a private / public SSH key pair on your local system
   ```bash
   ssh-keygen -t ed25519 -f ~/.ssh/id_ed25519_levante
   ```
-* Upload the public (`.pub`) key to your [DKRZ profile](https://luv.dkrz.de) ([instructions](https://docs.dkrz.de/doc/levante/access-and-environment.html)), so levante can check your connection attempts
-* Use your private ssh key instead of your password when connecting to levante
+* Upload the public (`.pub`) key to your DKRZ profile ([how to](https://docs.dkrz.de/doc/levante/access-and-environment.html#public-key-authentication))
+* Use your private SSH key to authenticate when connecting to levante
   ```bash
   ssh -i ~/.ssh/id_ed25519_levante <YOUR_USERNAME>@levante.dkrz.de
   ```
@@ -132,8 +122,8 @@ Different ways to work on a cluster depending on the task:
 * Create a config file for convenience
   ```{.sshconfig filename=~/.ssh/config}
   Host levante # the name you use in the shell
-     Hostname levante.dkrz.de # the official name of the system
-     User <YOUR_USERNAME> # add your user id
+     Hostname levante.dkrz.de # real host name of the system
+     User <YOUR_USERNAME> # your user id
      IdentityFile ~/.ssh/id_ed25519_levante # your private key
   ```
   (call `man ssh_config` for more info)
@@ -147,23 +137,16 @@ Different ways to work on a cluster depending on the task:
 
 ## Remote file transfer {auto-animate=true}
 
-* There are different tools to transfer between your local machine and a remote server
-* For single files, a simple `scp` is sufficient
-  ```{raw}
-  scp <YOUR_USERNAME>@levante.dkrz.de:file_in_home .
-  ```
-* `rsync` is a more powerful alternative
+* There are various tools to transfer data between your local machine and a remote server (e.g. [`scp`](https://linux.die.net/man/1/scp), [`rsync`](https://linux.die.net/man/1/rsync), [`uftp`](https://uftp-multicast.sourceforge.net))
+* `rsync` is a powerful option available on most machines
   ```{raw}
   rsync <YOUR_USERNAME>@levante.dkrz.de:file_in_home .
   ```
 
 ## Remote file transfer {auto-animate=true visibility="uncounted"}
-* There are different tools to transfer between your local machine and a remote server
-* For single files, a simple `scp` is sufficient
-  ```{raw}
-  scp levante:file_in_home .
-  ```
-* `rsync` is a more powerful alternative with more options
+
+* There are various tools to transfer data between your local machine and a remote server (e.g. [`scp`](https://linux.die.net/man/1/scp), [`rsync`](https://linux.die.net/man/1/rsync), [`uftp`](https://uftp-multicast.sourceforge.net))
+* `rsync` is a powerful option available on most machines
   ```{raw}
   rsync levante:file_in_home .
   ```
@@ -175,9 +158,11 @@ Different ways to work on a cluster depending on the task:
 |keep scripts | store output | temporary stuff |
 | small | big | big |
 | SSD | HDD | HDD |
-|backuped | no backup | deleted after 2 weeks |
+|backup | no backup | deleted after 2 weeks |
 
-We all lost data to `/scratch`, many killed something on `/work`
+::: {.fragment .fade-up}
+> Anything not saved will be lost --- _Nintendo_
+:::
 
 ## Compute nodes
 
@@ -191,7 +176,7 @@ We all lost data to `/scratch`, many killed something on `/work`
 ## Take home messages
 
 * High-performance computers like Levante are technically a cluster of numerous _normal_ computers that share the same hard disks
-* Using a secure shell (`ssh`) one can login to Levante and use it as any other machine
+* Using a secure shell (`ssh`) you can log into Levante and (mostly) use it like any other machine
 * Computationally demanding or long-lasting jobs have to be submitted to the job queue
 
 # Hands-on session {.handson}
@@ -215,7 +200,7 @@ We all lost data to `/scratch`, many killed something on `/work`
 
 ## tmux
 
-`tmux` enables to create and (re)attach to terminal sessions
+`tmux` enables to create and attach to terminal sessions
 
 * Crate a new session
   ```{raw}
@@ -229,10 +214,10 @@ We all lost data to `/scratch`, many killed something on `/work`
 
 ## X-forwarding
 
-You can use X-forwarding to forward graphical user interfaces (GUIs) from the server
+forward graphical user interfaces (GUIs) from the server
 
 * Install an X-server on your local machine (e.g. XQuartz)
-* Pass the `-X` option to your `ssh` command^[or check the SSH config option]
+* Pass the `-X`^[Mac users might want to use `-Y`, or MacOS will quit the forwarding after about 20 min.] option to your `ssh` command^[or check the SSH config option]
   ```{raw}
   ssh -X levante
   ```