I just found another really old laptop.
Just to play around I would like to make an ISO of my current installed system (including all installed software, configurations and data if possible) to avoid making a fresh install and doing it allover again!
Can I:
dd if=/dev/sda of=/home/limo/limotux.iso
to get a bootable ISO I can dd it to a flash disk to boot from and install on the other laptop?
Is it OK to create my new ISO on my /home?
That would just get you a copy of your device. Maybe better to call it “limotux.img”; img stands for image. You could then reverse this process and write the image to another device with dd. In effect you would be creating and restoring a copy/backup (“cloning”).
In fact, dd is one of the methods backup software like Clonezilla for example use to copy/write a disk/partition.
The image won’t be bootable on it’s own.
In my personal opinion, you’re making this more complicated than it needs to be. What you’re trying to accomplish is the cloning of a device. Software to do just this has been around for ages.
For example,
just download “Clonezilla Live”, create a booable USB, CD, whatever
boot it and create and store an image of your device
write (restore) this image to another device
Alternatively you can also directly clone a device to another attached device without storing an image.
You see, the image itself doesn’t need to be bootable.
Create an ESP and a Linux partition on your external drive with MBR instead of GPT
rsync your Linux install to external drive
Install GRUB in both BIOS and UEFI mode. BIOS installation is no different than doing to an installed system, you should use --removable flag for UEFI installation.
With this way, your installation will be cloned. It won’t be live / immutable, though.