The terminal

The desktop's terminal is derisk's own, derisk-terminal, from crates/derisk-terminal in derisk, and the image ships no other. It replaced foot, which the image carried only because derisk had no terminal. The virtual machine template's guest ships it too. Super+Enter opens one, as in i3 and sway. "Move to main pane", which had that key before, is now Super+Shift+Enter. Settings files saved before the change move over to the new keys if they still hold the old ones.

• Nerd Font icons. It draws the theme's monospace font from that font's Nerd Font build when one is installed. Glyphs a font lacks come from Symbols Nerd Font, then from the usual monospace fonts. The image installs Hack Nerd Font, since Hack is the theme's default, and the symbols-only Nerd Font, which supplies the icons when a theme names a font with no Nerd Font build. nixos/modules/desktop.nix installs both. An icon followed by a blank cell may span both cells, which is how Nerd Font icons are designed. Box drawing and block characters are drawn to fit the cell instead of taken from the font, so lines meet across cells in any font.
• On the GPU, or in software. It draws each frame on the GPU through OpenGL ES 3, or OpenGL 3.3, in one draw call, from an atlas of the glyphs it has drawn before. Where there is no GPU, or where OpenGL itself runs in software through llvmpipe, it draws the same frame on the CPU into shared memory instead, which is faster than llvmpipe. --renderer gpu or --renderer software picks one by hand.
• Deferred. What the shell prints only changes the grid. A frame is built from the grid when the compositor asks for one, so a command that prints a lot draws once per frame, not once per line.
• The desktop's theme. Colours and the font follow derisk's theme, and a change in Settings reaches a running terminal the next time it is focused.

It takes foot's command line, meaning a bare command or -e, -a/--app-id, -T/--title and -D. So a desktop entry written for foot runs in it with only the program's name changed.

checks.x86_64-linux.terminal, in nixos/tests/terminal.nix, starts it under cage in a VM with no GPU, where it has to choose software. It starts it again with --renderer gpu, where it has to draw through llvmpipe, and reads its text off the screen both times. The image's own boot test checks that the terminal, Hack Nerd Font and the symbols font are installed and foot is not.

The tools in the shell

The commands a person types are the Rust versions wherever a Rust version takes the GNU tool's options, on the host and in the guest template alike. nixos/modules/userland.nix sets this up:

Command	From
ls, cp, cat and the rest of coreutils	uutils coreutils
find, xargs, locate, updatedb	uutils findutils
gpg, gpgv, gpgconf	Sequoia's GnuPG chameleon, with sq beside it

The chameleon reads and writes GnuPG's own ~/.gnupg, so git's commit signing and anything else that runs gpg keep working, and secret keys stay with GnuPG's gpg-agent. The agent asks for a passphrase through pinentry-gnome3, which is gcr's dialog on the desktop and curses in a terminal with no display. Unlike GnuPG, the chameleon will not create ~/.gnupg itself, so each user manager makes it when it starts. Only chcon and runcon still come from GNU coreutils, because uutils leaves out those two, which only mean something under SELinux.

Some tools are still GNU, because the Rust version does not take the same options yet:

• diff, since uutils' has no -r, diff3 or sdiff;
• sed, since uutils' ignores -z, \U and \b, and gets sed 'n;d' wrong;
• ps and the rest of procps, since uutils' rejects ps aux;
• util-linux and tar, where uutils has only work in progress;
• grep, awk, less and gzip, which have no Rust version that takes their options.

Services and NixOS's own scripts run GNU throughout. NixOS sets their PATH, not the profile, and they were written against GNU. So does systemd-pull's check of an update's signature, which passes gpg --import-options=merge-only, an option the chameleon refuses.

important

There is no sudo, su or run0, and nothing that runs a command as root: pm system manages units and updates (pm on LosOS). The guest template keeps sudo-rs's su, since a guest has no pm service.

The image's boot test, nixos/tests/boot.nix, checks which of these answers ls, find and gpg. It makes a key with the chameleon, signs a file with it and verifies the signature. It verifies after signing instead of piping one gpg into another, because the chameleon's --verify reports a BAD signature when it reads one that a second gpg is still writing, even though the same bytes check out once written.