ググって出てくる色々な対処法を試したが駄目だったので真剣に何が起きているか調べた。

まずGUIのWSL設定ユーティリティを開いてセーフモード起動を有効にしてみると一応起動した。ただ sudo はModule is unknown、 systemctl はexec format errorで動かない。

無理やりrootでログインしてみる。

PS C:\Users\yk> wsl --user root -e zsh
wsl: SAFE MODE ENABLED - many features will be disabled
Gateau# ls -lS /usr/bin
total 159880
-rwxr-xr-x 1 root root   10322904 May  2 13:58  yay
-rwxr-xr-x 1 root root    8425600 Jul 21 18:16  xgettext
-rwxr-xr-x 1 root root    5841864 Apr 23 21:29  rsvg-convert

（中略）

-rwxr-xr-x 1 root root          0 Aug  2 04:56  bash
-r-xr-xr-x 1 root root          0 Aug  2 04:56  bashbug
-rwxr-xr-x 1 root root          0 Aug  6 02:50  bootctl
-rwxr-xr-x 1 root root          0 Aug  6 02:50  busctl
-rwxr-xr-x 1 root root          0 Aug  6 02:50  coredumpctl
-rwxr-xr-x 1 root root          0 Aug  6 02:50  homectl
-rwxr-xr-x 1 root root          0 Aug  6 02:50  hostnamectl
-rwxr-xr-x 1 root root          0 Aug  6 02:50  importctl
-rwxr-xr-x 1 root root          0 Aug  6 02:50  journalctl
-rwxr-xr-x 1 root root          0 Aug  6 02:50  kernel-install
-rwxr-xr-x 1 root root          0 Aug  6 02:50  localectl
-rwxr-xr-x 1 root root          0 Aug  6 02:50  loginctl
-rwxr-xr-x 1 root root          0 Aug  6 02:50  machinectl
-rwxr-xr-x 1 root root          0 Aug  6 02:50  networkctl
-rwxr-xr-x 1 root root          0 Aug  6 02:50  oomctl
-rwxr-xr-x 1 root root          0 Aug  6 02:50  portablectl
-rwxr-xr-x 1 root root          0 Aug  6 02:50  resolvectl
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemctl
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-ac-power
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-analyze
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-ask-password
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-cat
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-cgls
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-cgtop
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-creds
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-cryptenroll
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-cryptsetup
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-delta
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-detect-virt
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-dissect
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-escape
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-firstboot
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-hwdb
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-id128
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-inhibit
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-machine-id-setup
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-mount
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-notify
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-nspawn
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-path
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-repart
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-run
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-socket-activate
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-stdio-bridge
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-sysext
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-sysusers
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-tmpfiles
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-tty-ask-password-agent
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-vmspawn
-rwxr-xr-x 1 root root          0 Aug  6 02:50  systemd-vpick
-rwxr-xr-x 1 root root          0 Aug  6 02:50  timedatectl
-rwxr-xr-x 1 root root          0 Aug  6 02:50  udevadm
-rwxr-xr-x 1 root root          0 Aug  6 02:50  userdbctl
-rwxr-xr-x 1 root root          0 Aug  6 02:50  varlinkctl
-rwxr-xr-x 1 root root          0 Aug  3 22:38  wayland-scanner

/usr/bin の中身が色々と空になっている。なんじゃこれ。

とりあえず依存関係的に bash が必要なので、 bash を再インストールする。

pacman -S --overwrite "*" bash

これだけでセーフモード解除しても普通に起動するようになった。久々に冷や汗をかいた。