How to get the session numbers of every vncviewer background process and store them inside different variables - bash

Question

I like to play with the bhyve virtual machines in FreeBSD a lot. As you probably know,sometime when the OS loaded by the virtual machine is halted,the process of the virtual machine is not killed. This is not a bug,but the developers say that it is like this to speed up the booting process of the virtual machines. Now,I would like to create a script to kill the "dead" virtual machines that are still listed when I do a "ps ax | grep bhyve",but that can't be used anymore. Let's take the example below :
mario#marietto:/home/marietto # ps ax | grep bhyve
13720 - Is 0:00.00 bhyve: system.pwd (bhyve)
13721 - Is 0:00.00 bhyve: system.grp (bhyve)
13831 - Ss 0:00.00 bhyve: system.pwd (bhyve)
13832 - Ss 0:00.00 bhyve: system.grp (bhyve)
13826 4 SC+ 0:17.34 bhyve: vm2 (bhyve)
13715 1 IC+ 1:00.55 bhyve: vm4 (bhyve)
13852 3 S+ 0:00.00 grep bhyve
in this case I have two virtual machines called vm2 and vm4,that became ghosts because the os inside of them has been halted. To be clear,I want to show you how is the script that I usually use to launch a bhyve vm :
bhyve -S -c sockets=2,cores=2,threads=2 -m 8G -w -H -A \
-s 0,hostbridge \
-s 1,nvme,/dev/nvd0,bootindex=1 \
-s 2,virtio-blk,/dev/$vmdisk4 \
-s 3,virtio-blk,/dev/$vmdisk8 \
-s 4,virtio-blk,/dev/$vmdisk11 \
-s 10,virtio-net,tap2 \
-s 11,virtio-9p,sharename=/ \
-s 12,hda,play=/dev/dsp,rec=/dev/dsp \
-s 29,fbuf,tcp=0.0.0.0:5902,w=1600,h=950 \
-s 30,xhci,tablet \
-s 31,lpc \
-l bootrom,/usr/local/share/uefi-firmware/BHYVE_BHF_CODE.fd \
vm2 < /dev/null & sleep 2 && vncviewer 0:2
now,since there isn't any easy method to know if a virtual machine is a ghost or if it is running,I've thought to a system like this :
mario#marietto:/home/marietto # ps ax | grep vnc
13841 4 S+ 0:00.03 vncviewer 0:2
13727 1 S+ 0:00.04 vncviewer 0:4
13854 3 S+ 0:00.00 grep vnc
grepping the vncviewer session number is the most secure method to determine which virtual machine is really running because while a virtual machine is running really,I never close the vncviewer window but I minimize its window,and since I've associated the same number to the virtual machine and to the vncviewer session,I'm sure that the vm2 and vm4 are still running. When I will halt the vm2 and the vm4,the corresponding vnc sessions should be closed for sure. Now,what I want to do is to create a script that as output is able to give me 2 and 4,in that case. So,the script should assign the number 2 to the first variable and the number 4 to the second one :
$runvm1 = 2
$rvnvm2 = 4
Later I will complete the script like this :
bhyvectl --vm=$runvm1 --force-reset
bhyvectl --vm=$runvm1 --destroy
bhyvectl --vm=$runvm2 --force-reset
bhyvectl --vm=$runvm2 --destroy
because I want to reset and destroy all the ghost virtual machines that are still visible between the process listed with :
mario#marietto:/home/marietto # ps ax | grep bhyve

Answer 1

This will get your values.
#!/bin/sh
BASE=`basename "$0" ".sh" `
TMP="/tmp/tmp.$$.${BASE}"
echo "
mario#marietto:/home/marietto # ps ax | grep bhyve
13720 - Is 0:00.00 bhyve: system.pwd (bhyve)
13721 - Is 0:00.00 bhyve: system.grp (bhyve)
13831 - Ss 0:00.00 bhyve: system.pwd (bhyve)
13832 - Ss 0:00.00 bhyve: system.grp (bhyve)
13826 4 SC+ 0:17.34 bhyve: vm2 (bhyve)
13715 1 IC+ 1:00.55 bhyve: vm4 (bhyve)
13799 8 IC+ 1:00.55 bhyve: abc_vm4 (bhyve)
13852 3 S+ 0:00.00 grep bhyve
" >${TMP}.testinput
cat "${TMP}.testinput" | grep '(bhyve)' |
awk '{
if( $6 ~ /^vm/ ){
id=substr( $6, 3 ) ;
printf("%s|%s|%s\n", id, $6, $1 ) ;
} ;
### Sample output:
### 2|vm2|13826
### 4|vm4|13715
}' |
awk -F \| 'BEGIN{ indx=0 ; }{
indx++
printf("runvm"indx" = %s\n", $1 ) ;
### Sample output:
### runvm1 = 2
### runvm2 = 4
}'