How to use qemu to run a non-gui OS on the terminal?

Question

I want to run some programs on the High Performance Computer (With 8-core processor) in my department. Now I use that machine with ssh using terminal. The machine has Red Hat li

Answer 1

Linux: -append 'console=ttyS0'

That option was also needed for Linux kernel be besides -nographic mentioned by osgx as in:

qemu-system-x86_64 -append 'console=ttyS0' \
                   -initrd rootfs.cpio.gz \
                   -kernel bzImage \
                   -nographic \
                   -serial mon:stdio \
                   

Now you can do the following:

• Ctrl + A X: exit qemu, see: https://superuser.com/questions/1087859/how-to-quit-the-qemu-monitor-when-not-using-a-gui
• Ctrl + C: gets passed to the guest

-append 'console=ttyS0' makes QEMU pass the console=ttyS0 kernel command line option to LInux, which tells the kernel to use a serial port instead of the display. The serial port sends characters between host and guest, instead of pixels on a display, and then QEMU can display those characters on the terminal.

-serial mon:stdio is optional in this minimal command, but it is generally a good idea to have around. E.g., it improves behaviour if you also want to add a handy -monitor telnet later on:

• How to run qemu with -nographic and -monitor but still be able to send Ctrl+C to the guest and quit with Ctrl+A X?
• https://unix.stackexchange.com/questions/167165/how-to-pass-ctrl-c-to-the-guest-when-running-qemu-with-nographic

This can be easily tested with Buildroot qemu_x86_64_defconfig. I've created this is a highly self-contained and automated setup that allows you to try this out easily

Related but with less OS constraints:

• redirect QEMU window output to terminal running qemu
• Redirect Qemu console to a file or the host terminal?

Tested on Ubuntu 18.04, QEMU 2.11.1.

FreeBSD

How to boot FreeBSD image under Qemu