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scoot — a grumpy ginger cat about to swat a window sidewaysscoot

Terminal, files, and removable media

The compositor’s built-in Super+Return opens foot, so the profile installs foot, since a bind that names a missing binary is a dead key. The look themes it (the terminal target writes foot.ini); this slot owns the package, TERMINAL=foot for anything that asks, and the plumbing every “open this” goes through:

  • xdg-open (xdg-utils) on PATH, and BROWSER=xdg-open: a link opens through your x-scheme-handler/https default. The profile ships no browser.
  • The XDG user dirs exist (xdg.userDirs, created on activation): ~/Downloads, ~/Pictures (where screenshots land), ~/Documents and the rest.
  • With the file manager on, directories open in it: inode/directory and inode/mount-point, the type of /tmp and of every mounted drive (without the second, xdg-open on a mount falls through to a browser).

The file manager is optional and off. Turn it on for mouse-driven browsing:

configuration.nix and home.nix
programs.scoot.desktop.apps.fileManager.enable = true;   # pcmanfm

Without it xdg-open keeps working for files and links. A directory has no default then, and xdg-open falls back to a web browser’s file listing if one is installed, or “no method available” if not. Nothing hangs.

A default text editor makes git, xdg-open on a text file and every EDITOR reader agree:

configuration.nix and home.nix
programs.scoot.desktop.apps.editor.default = "nvim";   # or "helix"

Set: the editor installs (Neovim follows the look’s colorscheme), EDITOR and VISUAL name its binary (at mkOverride 900: beating nixpkgs’ nano default, losing to a plain assignment, merging with programs.neovim.defaultEditor on the same value), and text/plain (and text/*) opens through a generated entry running foot -e <editor> %F (the terminal option’s binary). Your own EDITOR, VISUAL or text association wins outright over the profile’s. null (the default) installs and sets nothing; a null package beside a set default fails evaluation naming it.

Removable media mounts on insert: udiskie runs trayless as a user unit (scoot-automount.service, wanted by scoot-session.target) over the udisks2 daemon the NixOS side enables. Insert a drive and it mounts under /run/media/$USER/, with a notification whose Browse action opens the mount through xdg-open (the file manager, when it is on). An encrypted (LUKS) drive asks for its passphrase, then mounts its unlocked filesystem the same way. It runs on udiskie’s stock device rules, which leave the machine’s own disks alone: udisks2 marks an internal disk HintSystem, and udiskie skips it and every partition on it, so a dual-boot box’s Windows or macOS partitions stay unmounted, with no admin prompt at login. A ~/.config/udiskie/config.yml of your own still applies (the unit passes no -c; its -a -n -T flags win over the file’s). A file udiskie cannot parse makes every start fail, so the unit gives up after 5 failed starts in a minute (see troubleshooting below). With home-manager’s own services.udiskie on, that one runs instead and this unit stays out, because two automounters would race to mount every drive. udiskie stays installed either way, so udiskie-umount is there for safe removal.

Safe removal: unmount before you unplug. A yanked drive loses whatever was still buffered. One command unmounts and powers it off:

Terminal window
udiskie-umount -d /run/media/$USER/LABEL

Wait for the command to return, then unplug. udiskie-umount -a unmounts every drive udiskie handles at once; the machine’s own disks are not among them.

Measured on the M2 (aarch64-linux) at the pinned rev (8ce4ef6): full closures by nix path-info --closure-size; “new over the profile” is the store paths the tool adds to the whole desktop profile (system built with and without the slot); idle cost is VmRSS and context switches over every process the app brought (D-Bus-activated helpers included) under a headless scoot in its own dbus-run-session, summed over the threads alive across 60 s idle after a 30 s settle:

File manager Version Full closure New over the profile Idle RSS Idle wakeups Left after closing Why / why not
pcmanfm 1.4.0 347.3 MiB 5.3 MiB (4 paths: itself, libfm, libfm-extra, menu-cache) ~50 MB 0 in 60 s nothing the pick: the smallest closure and marginal, its GTK 3 already in the profile, silent at idle, gone when closed
thunar 4.20.9 376.2 MiB 27.0 MiB (13 paths) ~52 MB 2 in 60 s nothing as quiet and as light at runtime, five times the marginal (the xfce libraries)
yazi (in foot) 26.9.1 524.7 MiB 75.1 MiB (13 paths) ~54 MB with its foot (~27 MB without) 418 in 60 s nothing the terminal shape, but wrapped with its previewers it is the heaviest closure, and its async runtime wakes about seven times a second at idle

pcmanfm is the smallest everywhere it differs, and nothing is left running once its window closes (no menu-cached, gvfsd or thumbnailer). Point fileManager.package at another (with its desktopEntry) to choose differently.

The automounter, measured the same way live in the session (its own unit, after the drive test below):

Process Idle RSS Idle wakeups Closure over the profile
udiskie, trayless (the unit) ~58 MB 0 in 60 s 48.1 MiB (35 paths: Python, PyGObject, docopt, PyYAML)
udisksctl monitor (the floor a hand-rolled automounter would start from) ~8 MB 0 in 60 s 0 (ships with udisks2)
udisksd (needed either way) ~18 MB 0 in 60 s, with /etc/nvme present (see below) ~25 MiB more with its filesystem tools (the slot is 73.5 MiB, 70 paths, in all)

Neither polls. udiskie costs about 50 MB more than the bare floor, for per-partition handling, an encrypted-drive passphrase prompt, the Browse action, the device rules above, and udiskie-umount for safe removal.

The profile also creates /etc/nvme (an empty /etc/nvme/.keep, through environment.etc, so it exists under an immutable /etc too). udisksd watches that directory (NVMe-oF host identity), and GLib retries a watch on a missing path every 4 seconds: 15 wakeups a minute, forever, measured on the M2 (all inotify_add_watch("/etc/nvme") = ENOENT), and 0 once the directory exists.

Every value is an option, applied on rebuild/switch (the unit restarts with the new config; a new TERMINAL or BROWSER reaches apps started after the next login):

Option Type Default Meaning
desktop.apps.terminal.enable bool true with the profile foot on PATH (left to home-manager’s programs.foot when that is on: its package wins), TERMINAL=foot
desktop.apps.terminal.package package or null foot (Linux-only: null off Linux) the terminal to install; the compositor’s Super+Return still names foot, so another terminal also needs that bind
desktop.apps.fileManager.enable bool false the file manager on PATH, directories and mounts opening in it
desktop.apps.fileManager.package package or null pcmanfm (Linux-only: null off Linux) point at another file manager
desktop.apps.fileManager.desktopEntry string "pcmanfm.desktop" the .desktop entry directories open through ("thunar.desktop" beside a thunar package)
desktop.apps.editor.default null, "nvim" or "helix" null the default text editor: installs it, sets EDITOR and VISUAL (at mkOverride 900: beating nixpkgs’ nano default, merging with programs.neovim.defaultEditor), and answers text/plain (and text/*) through a terminal entry running it (foot -e <editor>, following the terminal option); null installs and sets nothing
desktop.apps.editor.package package or null neovim or helix, following the default (Linux-only: null off Linux) the default editor to install (left to home-manager’s programs.neovim/programs.helix when that is on: its package wins)
desktop.automount.enable bool true with the profile udisks2 on the NixOS side, udiskie and its trayless unit on the home-manager side (the unit left out while home-manager’s services.udiskie is on: its unit runs instead)
desktop.automount.package package or null udiskie with its flaky keyring tests off (Linux-only: null off Linux) point at your own udiskie build

A null package beside its switch fails evaluation naming it. xdg-open, BROWSER and the user dirs come on with the terminal or the file manager (and xdg-open/BROWSER with the automounter, for its Browse action). Your own xdg.userDirs and xdg.mimeApps values win outright over the profile’s: xdg.userDirs.enable = false (no ~/Music and friends) or a xdg.mimeApps.defaultApplications."inode/directory" of your own replaces the profile’s, with no conflict and no merged list.

Troubleshooting, by symptom:

  • Activation stops: “Existing file ‘…/.config/user-dirs.dirs’ would be clobbered” (or mimeapps.list). A file you (or an app) wrote is in the way of the one the profile manages. Move it aside, or set home-manager’s backupFileExtension so activation moves it for you.
  • A browser cannot make itself the default. With the file manager on, ~/.config/mimeapps.list is the profile’s, read-only. Set the default there instead: xdg.mimeApps.defaultApplications."x-scheme-handler/https" = "firefox.desktop"; (and x-scheme-handler/http, text/html).
  • A drive does not mount. systemctl --user status scoot-automount first: skipped (condition failed) means no udisks2 on the system bus; a home-manager-only setup needs services.udisks2.enable on the system. Running but nothing mounted: udisksctl status lists what udisks2 sees, and udisksctl mount -b /dev/sdX1 names the refusal. failed with start-limit-hit means udiskie failed 5 starts in a minute: journalctl --user -u scoot-automount shows why, most often a ~/.config/udiskie/config.yml it cannot parse. Fix (or move) the file, then systemctl --user reset-failed scoot-automount and systemctl --user start scoot-automount.
  • An internal partition does not automount. By design (above): mount it by hand with udisksctl mount -b /dev/..., which asks for the admin password.