Merge branch 'command-line-additions' into 'main'

Command line additions

See merge request generic-software-skills/lecture-materials!36

lectures/command-line/slides.qmd

@@ -108,6 +108,7 @@ Different ways to work on a cluster depending on the task:
   ```{raw}
   ssh a123456@levante.dkrz.de
   ```
+  (use your user id instead of a123456)
 * Now you have access to the command line on levante
 
 ## Public keys
@@ -116,13 +117,13 @@ Different ways to work on a cluster depending on the task:
 
 ## Generating SSH keys
 
-* Generate an ssh key pair
-  ```{raw}
+* Generate a private / public ssh key pair for authentication 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)
-* Use your ssh key instead of your password when connecting to levante
-  ```{raw}
+* 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
+  ```bash
   ssh -i ~/.ssh/id_ed25519_levante a123456@levante.dkrz.de
   ```
 
@@ -130,11 +131,12 @@ Different ways to work on a cluster depending on the task:
 
 * Create a config file for convenience
   ```{.sshconfig filename=~/.ssh/config}
-  Host levante
-     Hostname levante.dkrz.de
-     User a123456
-     IdentityFile ~/.ssh/id_ed25519_levante
+  Host levante # the name you use in the shell
+     Hostname levante.dkrz.de # the official name of the system
+     User a123456 # your user id
+     IdentityFile ~/.ssh/id_ed25519_levante # your private key
   ```
+  (call `man ssh_config` for more info)
 
 * The connection to levante simplifies to
   ```{raw}
@@ -239,3 +241,8 @@ You can use X-forwarding to forward graphical user interfaces (GUIs) from the se
 
 * SSH keys at DKRZ expire after a month
 * When using a hardware authenticators (e.g. YubiKey) the key is valid for a year
+
+# References
+
+* [Software Carpentry: The Unix Shell](https://swcarpentry.github.io/shell-novice/)
+* [Software Carpentry Incubator: Unix Shell Extras (incl. ssh)](https://carpentries-incubator.github.io/shell-extras/)
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