qubes-installer-qubes-os/anaconda/data/systemd/anaconda-noshell.service

[Unit]
Description=Restrict Anaconda Text Console
After=anaconda.service
Before=anaconda-tmux@.service
ConditionKernelCommandLine=|inst.noshell
ConditionKernelCommandLine=|noshell

[Service]
Type=oneshot
WorkingDirectory=/root
ExecStart=/usr/bin/tmux unbind-key -a; \
                        kill-window -t anaconda:shell; \
                        bind-key 1 select-window -t :1; \
                        bind-key 2 select-window -t :2; \
                        bind-key 3 select-window -t :3; \
                        bind-key 4 select-window -t :4; \
                        bind-key 5 select-window -t :5; \
                        bind-key ? list-keys