Use the ONESHOT mode to prompt "the command is REPL only."

[Shonke]

my operation record is here:

~/Desktop$ termtunnel ssh root@my_machine_ip
Linux 5.10.0-15-amd64 #1 SMP Debian 5.10.120-1 (2022-06-09) x86_64

The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
Last login: Thu Jan 19 21:03:27 2023 from xx.xx.xx.xxx
Welcome to fish, the friendly interactive shell
root ~# termtunnel -- remote_listen 127.0.0.1 7890 127.0.0.1 7890
the command is REPL only.
end
root ~# 
root ~# export
DBUS_SESSION_BUS_ADDRESS unix:path=/run/user/0/bus
HOME /root
LANG en_US.utf8
LANGUAGE en_US.utf8
LC_TERMINAL iTerm2
LC_TERMINAL_VERSION 3.4.15
LOGNAME root
MOTD_SHOWN pam
NODE_EXTRA_CA_CERTS /usr/local/share/ca-certificates/root_ca.crt
PATH '/root/.local/bin'  '/usr/bin'  '/run/us$
PWD /root
SHELL /usr/bin/fish
SHLVL 1
SSH_CLIENT 'xxx.xx.xx.xxx 8396 22'
SSH_CONNECTION 'xxx.xx.xx.xxx 8396 10.40.0.8 22'
SSH_TTY /dev/pts/2
TERM xterm-256color
USER root
XDG_RUNTIME_DIR /run/user/0
XDG_SESSION_CLASS user
XDG_SESSION_ID 45416
XDG_SESSION_TYPE tty
root ~#
root ~# ^D
Connection to xx.xx.xx.xxx closed.
~/Desktop$ termtunnel ssh -tt root@my_machine_ip termtunnel -- remote_listen 127.0.0.1 7890 127.0.0.1 7890
the command is REPL only.
end
Connection to xx.xx.xx.xxx closed.3AqAFvwKgBbwEswagAABmgAAAZdFAQ+f87vQAA!
~/Desktop$