Trouble with AWK'd command output and bash array

Question

I am attempting to get a list of running VirtualBox VMs (the UUIDs) and put them into an array. The command below produces the output below:

$ VBoxManage list runningvms | awk -F '[{}]' '{print $(NF-1)}' 

f93c17ca-ab1b-4ba2-95e5-a1b0c8d70d2a
46b285c3-cabd-4fbb-92fe-c7940e0c6a3f
83f4789a-b55b-4a50-a52f-dbd929bdfe12
4d1589ba-9153-489a-947a-df3cf4f81c69

I would like to take those UUIDs and put them into an array (possibly even an associative array for later use, but a simple array for now is sufficient)

If I do the following:

array1="( $(VBoxManage list runningvms | awk -F '[{}]' '{print $(NF-1)}') )"

The commands

array1_len=${#array1[@]}
echo $array1_len

Outputs "1" as in there's only 1 element. If I print out the elements:

    echo ${array1[*]}

I get a single line of all the UUIDs

( f93c17ca-ab1b-4ba2-95e5-a1b0c8d70d2a 46b285c3-cabd-4fbb-92fe-c7940e0c6a3f 83f4789a-b55b-4a50-a52f-dbd929bdfe12 4d1589ba-9153-489a-947a-df3cf4f81c69 )

I did some research (Bash Guide/Arrays on how to tackle this and found this with command substitution and redirection, but it produces an empty array

while  read -r -d '\0'; do
        array2+=("$REPLY")
    done < <(VBoxManage list runningvms | awk -F '[{}]' '{print $(NF-1)}')

I'm obviously missing something. I've looked at several simiar questions on this site such as:

Unfortunately, none have helped. I would apprecaite any assistance in figuring out how to take the output and assign it to an array.

I am running this on macOS 10.11.6 (El Captain) and BASH version 3.2.57

Remove the double-quotes: array1=( $(VBoxManage list runningvms | awk -F '[{}]' '{print $(NF-1)}') ), (The entries will be subject to word-splitting and pathname expansion but that doesn't appear to be a problem here.) — John1024
– John1024, Commented Dec 4, 2017 at 21:44
You were also very close with your while. If you change it to just: while read -r; do, it will work too. — PesaThe
– PesaThe, Commented Dec 4, 2017 at 22:58
@John1024 - the double quotes did it. Out of curiosity, (even though it's moot), how would I approach this if there were spaces that led to word splitting since the quotes made the whole output a single long string? — Allan
– Allan, Commented Dec 5, 2017 at 11:35
@PesaThe - Thanks! I thought I had to account for a null char based on what I read/understood). — Allan
– Allan, Commented Dec 5, 2017 at 11:37

peak · Accepted Answer · 2017-12-05 16:02:44Z

1

Since you're on a Mac:

brew install bash

Then with this bash as your shell, pipe the output to:

readarray -t array1

Of the -t option, the man page says:

-t     Remove a trailing delim (default newline) from each line read.

If the bash4 solution is admissible, then the advice given e.g. by gniourf_gniourf at reading-output-of-command-into-array-in-bash is still sound.

edited Dec 5, 2017 at 16:02

answered Dec 5, 2017 at 0:52

peak

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1 Comment

Allan Over a year ago

It's a good solutions, however, I can't use it. I don't like writing scripts that are dependent on specific environments. Many times, I share the script or I cannot install a port/brew making my solution unworkable. I try to keep everything as native as possible.

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