computer notes - cool things I just learned + things I always forget

things to remember.md

1. show your IP Address, Linux CLI (RIP ifconfig 😢) (ref)

   • ip address (kinda embarassing how simple this is.. hopefully just writing this will help me remember)

2. rotate the Linux CLI, if you have a monitor in portrait orientation (ref)

   • echo 1 | sudo tee /sys/class/graphics/fbcon/rotate
   • 0 = normal, 1 = clockwise, 2 = upside down, 3 = counter-clockwise
   • make it permanent
     • in /etc/default/grub: GRUB_CMDLINE_LINUX="fbcon=rotate:1"
     • sudo update-grub

3. executing vs sourcing shell scripts (ref)

   • source command runs the script in your current shell instance, . <script> is equivalent to source
   • when you execute a script, it runs in its own shell instance with its own vars etc
   • exec command kills the current shell and replaces it with whatever script or command you supply

4. Check which shell you're using (ref)

   • echo $0
   • Note that $SHELL needs to be manually updated (at least on Mac) so echo $SHELL isn't reliable

5. Key based SSH auth for Mac etc (ref)

   • From the Mac / client side
     • ssh-keygen
     • ssh-copy-id
     • to skip the passphrase each time, ssh-add (see ref link above)

6. Boot from USB:

   • Mac: press & hold Option key when you see the Apple
   • Dell: F12 at logo (YMMV / WFM)

7. Get Debian, Ubuntu etc to install all the packages: sudo apt-get --with-new-pkgs upgrade (ref)

   • NOTE: no need to worry about updates that aren't installed due to phasing

8. Use multipass as non-root: (ref)

   • (as root) multipass set local.passphrase
   • (as user) multipass authenticate

9. Use /home for multipass storage instead of /root

   • NOTE it has to be /home or a removable device b/c of snap confinement
   • this guide works, follow the instructions exactly
   • OR, instead of the cp commands at the end, you can also just reinsatll multipass, it will populate the storage dir
   • ? might be easier to just symlink data and cache dirs, something to try next time

10. Use git with GitHub: (ref)

    • ssh-keygen -t rsa -b 4096 -C "[email protected]"
    • copy the correct line from ~/.ssh/id_rsa.pub to https://github.com/settings/keys
    • git remote set-url origin [email protected]:username/your-repository.git
      • or if your repo is in an org: git remote set-url origin [email protected]:organization/your-repo.git
    • ssh-add ~/.ssh/id_rsa

11. Encrypted volumes, the systemd way (ref)

    • NOTE you don't need to be root to use the udisksctl command
    • mount

udisksctl unlock -b /dev/sdb5
udisksctl mount -b /dev/mapper/ubuntu--vg-root

• unmount
  • If this is a volume group, you'll need to deactivate before locking it: sudo lvchange -an ubuntu-vg

udisksctl unmount -b /dev/mapper/ubuntu--vg-root
udisksctl lock -b /dev/sdb5