How can I figure out which pty's are from which qemu?

Question

I'm running qemu's like this:

$ sudo qemu -boot d -m 1024 \
-netdev tap,id=tap0 \
-device virtio-net-pci,netdev=tap0,id=vth0 \
-drive file=ubuntu.iso,media=cdrom,cache=none,if=ide \
-monitor pty \
-serial pty \
-parallel none \
-nographic

When I check /dev/pts/:

$ sudo lsof +d /dev/pts/

Qemu pty's do not show up, although they do work using for example:

$ sudo screen /dev/pts/8

How can I figure out which pty's are from which qemu?

Answer 1

You can do it this way using virsh along with some scripting:

$ for i in `virsh list | awk '{print $2}' | egrep -v "^$|Name"`; do
     printf "%-14s:%s\n" $i $(virsh ttyconsole $i | grep -v "^$");
  done

cobbler       :/dev/pts/1
xwiki         :/dev/pts/3
fan           :/dev/pts/4
mercury       :/dev/pts/5
mungr         :/dev/pts/0
win2008R2-01  :/dev/pts/7

Incidentally those same VMs through an lsof command:

$ lsof|grep qemu|grep ptmx
qemu-kvm   3796      root   14u      CHR                5,2         0t0        993 /dev/ptmx
qemu-kvm   3895      root   14u      CHR                5,2         0t0        993 /dev/ptmx
qemu-kvm   3972      root   14u      CHR                5,2         0t0        993 /dev/ptmx
qemu-kvm   4294      root   15u      CHR                5,2         0t0        993 /dev/ptmx
qemu-kvm  11897      root   14u      CHR                5,2         0t0        993 /dev/ptmx
qemu-kvm  16250      root   15u      CHR                5,2         0t0        993 /dev/ptmx

It doesn't look like lsof shows which pty they're using, just that they're using the ptmx. See the ptmx man page for more info.

References

• Setting up a serial console in qemu and libvirt

The left side are the names of the VMs and the right side is the pts.