Get a list of running VMs using VBoxManage

Question

I want to loop through my running VM's and return only what is between quotes.

So this command:

VBoxManage list runningvms

returns:

"UbuntuServer" {7ef01f8d-a7d5-4405-af42-94d85f999dff}

And I only want it to return:

UbuntuServer

This is what i have so far (fail):

#!/bin/bash
for machine in `cat VBoxManage list runningvms`; do
        echo "$machine"
done
exit

Answer 1

VBoxManage list runningvms | cut -d '"' -f 2 | while read machine; do
   echo "$machine"
done

Answer 2

Warning: all of this is is risky if your VM names have shell glob characters in them, or contain spaces.

---

You can do something like this if there is only one running VM:

read machine stuff <<< $(VBoxManage list runningvms)
echo "$machine"

Alternative with bash arrays (same condition):

vbm=($(VBoxManage list runningvms))
echo "${vbm[0]}"

If that program returns more than one line, a more classic approach would be:

for machine in $(VBoxManage list runningvms|cut -d" " -f 1); do
  echo "$machine"
done

Answer 3

for one-liner fans:

VBoxManage list runningvms | cut -d" " -f 1 | grep -oP "(?<=\").*(?=\")"

Answer 4

To validate each line as you read it, the safe way to do this is to write a regular expression and use BASH_REMATCH to extract match groups from it.

With the following code:

re='^"(.*)" [{]([0-9a-f-]+)[}]$'
while read -r line; do
  if [[ $line =~ $re ]]; then
    name=${BASH_REMATCH[1]}; uuid=${BASH_REMATCH[2]}
    echo "Found VM with name $name and uuid $uuid" >&2
  else
    echo "ERROR: Could not parse line: $line" >&2
  fi
done < <(VBoxManage list runningvms)

...and the following mock implementation of VBoxManage (to allow folks without VirtualBox to reproduce the test):

VBoxManage() { printf '%s\n' '"UbuntuServer" {7ef01f8d-a7d5-4405-af42-94d85f999dff}'; }

...output is as follows:

Found VM with name UbuntuServer and uuid 7ef01f8d-a7d5-4405-af42-94d85f999dff

---

Note advantages of this approach:

• It doesn't make unfounded assumptions, such as excluding virtual machines with whitespace or quote literals in their names from support.
• It detects any line that doesn't match the expected pattern, rather than behaving in an unanticipated way in the presence of such values.
• It still behaves correctly with data that does match the pattern but has unanticipated values. (For instance, a virtual machine named * won't have that name silently replaced with the name of a file in the current directory).
• It doesn't involve tools external to the shell such as sed, cut, &c., but relies purely on shell-builtin functionality -- see BashFAQ #1 documenting the use of while read, and the bash-hackers' wiki on regular expression matching documenting [[ $string =~ $re ]].