You need to install packman
(https://github.com/lyqyd/cc-packman#12---automatic-pastebin-installation)
Currently the command to run on you ComputerCraft PC is: pastebin run 4zyreNZy
Now you can reboot you ComputerCraft PC and run packman install nsh
It will ask you to confirm, type Y then enter
You need to add a label to you computer: label set <your_computer_name>
After installing nsh, you can install secure-nsh by typing packman install secure-nsh-login
It will ask you to confirm, type Y then enter
You need to modify the startup script to add nsh at startup.
First, backup the script cp /startup /startup.backup
then open the file by typing edit /startup
Add this line at the end: shell.run("/usr/bin/nsh host /usr/bin/secure-nsh-login")
Then reboot the computer by typing reboot
and nsh is installed
The default user is root
and his password is root
The help is available by typing secure-nsh help