# ssh config
## Copy keys to rsync.net
You have to use the dd method to append your keys as the sshconfig doesn't allow `ssh-copy-id`:
```
cat ~/.ssh/id_rsa.pub | ssh
[email protected] 'dd of=.ssh/authorized_keys oflag=append conv=notrunc'
```
# Disk Images, isos, etc
Copy physical DVD to iso
```bash
dd if=/dev/dvd of=dvd.iso
```
# Package Management
<span style="font-size:11.142857551574707pt;">Show Installed packages</span>
```bash
apt-show-versions
OR
dpkg --get-selections
```
<span style="font-size:11.142857551574707pt;">Alternatly, sync packages between machines:</span>
```
dpkg --get-selections > selections.txt
```
move selections.txt to the new machine Set package list on new machine and install packages
```bash
dpkg --set-selections < selections.txt
apt-get update
apt-get upgrade
```
# File Systems
## making btrfs file system
```bash
sudo apt install btrfs-tools
sudo fdisk -l
sudo mkfs.btrfs -f -O ^extref -L ZeroDrive /dev/sda
```
## auto mount btr.fs
```bash
sudo blkid /dev/sda
sudo mkdir /ZeroDrive
sudo vi /etc/fstab
sudo chown pi:adm /ZeroDrive/
```
```bash
sudo btrfs filesystem show
```
```bash
btrfs filesystem df
sudo btrfs filesystem df /ZeroDrive/
```