Liberate your terminal from the boundaries of the 80x25 serial console

As a sysadmin, I use SSH a lot. More accurately, my world revolves around SSH.

ESTL’s apps run in virtual machines, but I have to manage the bare metal servers when the occasional need arises. KVM is the hypervisor we use, and sometimes (esp. when the VM goes bonkers and I cannot SSH in), I have to access the VM via a virtual TTY console (ie. virsh console theNameOfTheVM).

This is the normal workflow when the VM behaves.

laptop$ ssh serverA
serverA$ ssh vm1
vm1$ ./do_my_stuff

This is the workflow when the VM misbehaves.

laptop$ ssh serverA
serverA$ virsh console vm1
vm1$ ./do_my_stuff

The shell provided by libvirt’s virsh console is exactly like SSH’s in functionality except for one caveat — the shell is limited to a TTY serial console (think: RS-232 era) 80 columns by 25 rows.

Help! I’m stuck in a virtual 80x25 box!

If you use virsh console and ended up stuck in a 80-by-25 screen, you’re not alone. No, do not close your terminal and reopen it. No, do not call the Ghostbusters.

The magic word to get yourself out of this terrible trap is…

reset

If you were expecting more, sorry to disappoint. Run the reset command in the KVM host, and not in the VM. What reset does is basically to reinitialise the terminal, and voilà! the limits set by virsh console.

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