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+# making custom arch linux live ISOs without arch linux
+
+2023-06-07
+
+If you've ever installed any Linux distro, you probably had to do it using a live install environment.
+Once you flashed the USB drive, you could boot off it and you'd be greeted with a Linux system.
+
+I've always found it fascinating that you could pack the entire OS onto a stick and bring it around with you.
+However, something even more enticing is being able to customize that system.
+
+This is where archiso comes in handy:
+it's a tool that can be used to generate ISOs with Arch Linux on them.
+You can flash these ISOs to USB drives to make portable Arch Linux systems.
+archiso is also incredibly flexible, and you can customize it very well.
+In fact, it's the tool that Arch's maintainers use to generate the official live installation images.
+
+The one issue I have, though is that you need to be running Arch Linux to run archiso:
+
+> Currently creating the images is only supported on Arch Linux but may work on other operating systems as well.
+
+As I run another distro on my laptop, I could not use archiso.
+So, in the last few days, I set out to make archiso run on my system.
+The final results of this endeavour can be found [on GitHub](https://github.com/dogeystamp/archiso-portable).
+
+## pacstrap
+
+One of the essential dependencies of archiso is pacstrap.
+Essentially, what pacstrap does is that it creates a small Arch Linux system in a folder.
+This is the bootstrapped root filesystem (root FS).
+Later, archiso takes that folder, compresses it, and puts it in the final ISO file.
+
+The problem is that pacstrap needs your host system to be Arch Linux so that it can bootstrap a new Arch system.
+In fact, if you look at the [source code](https://github.com/archlinux/arch-install-scripts/blob/master/pacstrap.in),
+you'll find that the host system uses its own pacman to install everything to the bootstrapped system:
+
+    pacman -r "$newroot" "${pacman_args[@]}"
+
+pacstrap only has to create a few directories, but the rest is done by installing the `base` metapackage through pacman.
+`base` includes both `filesystem` and `pacman`.
+As far as I understand, this means that all the important files in an Arch Linux system come from installing the `filesystem` package.
+Once the host pacman installs `base` in the bootstrapped system, we have a full Arch Linux root FS, including its own pacman.
+
+However, since I do not have pacman to bootstrap this way, I needed another way to obtain an Arch root FS.
+I came across [archstrap](https://github.com/wick3dr0se/archstrap), which does exactly that.
+archstrap downloads a pre-built Arch Linux root FS as a tarball, then installs packages to it just like regular pacstrap.
+Cleverly, this script removes the need for arch-chroot on the host system:
+it runs the arch-chroot inside the downloaded Arch filesystem.
+
+Somewhat annoyingly though, archstrap does not operate exactly the same way pacstrap does:
+I had to patch it to get it working with archiso.
+Also, I patched archiso itself to remove some flags archstrap doesn't parse.
+
+## other changes
+
+The other main dependency missing in archiso is pacman, Arch's package manager.
+Since we aren't running Arch, we of course do not have it on our host system.
+However, the bootstrapped Arch root FS we downloaded earlier does have pacman inside of it.
+Therefore, I replaced all invocations of pacman inside archiso with invocations of the bootstrapped pacman.
+
+archiso also includes a small script to test your generated ISOs in a QEMU virtual machine.
+I added a check to it that switches some hard-coded paths.
+In Arch, the path is `/usr/share/edk2-ovmf/x64`,
+but on my system it was at `/usr/share/edk2-ovmf`.
+
+## conclusion
+
+It turns out that modifying open source software isn't that difficult.
+Given that archiso's maintainers wrote very structured and organized code,
+it's surprisingly easy to navigate around the script to patch things.
+
+Of course, I definitely ruined the quality of archiso by doing this:
+there's missing features and everything is untested and unlinted.
+Then again, this isn't going to be production-grade software;
+I just wanted to make a custom portable Arch USB while using Gentoo on my PC.
+
+Anyways, if you want to make your own custom Arch USBs but don't have Arch,
+check out [archiso-portable](https://github.com/dogeystamp/archiso-portable) on GitHub.
+
+As a bonus, here's a screenshot of the Arch Linux live environment I made earlier on a Gentoo system:
+
+![preview](/public/img/archiso-portable-desktop.jpg)