Bash – Error running a startup-script: home environment variable not set in redhat instance running on GCP

I'm having trouble to understand the shell environement that is used to run startup scripts. What difference with a login session?

If I set a simple starup script to print the env variables:

metadata
items:
- key: startup-script
value: ' printenv;'


I will have something like this:
Feb 20 15:16:19 xxxx startup-script[1112]: INFO startup-script: OLDPWD=/
Feb 20 15:16:19 xxxx startup-script[1112]: INFO startup-script: PATH=/usr/local/sbin:/usr/local/bin:/usr/
Feb 20 15:16:19 xxxx startup-script[1112]: INFO startup-script: PWD=/opt
Feb 20 15:16:19 xxxx startup-script[1112]: INFO startup-script: LANG=en_US.UTF-8
Feb 20 15:16:19 xxxx startup-script[1112]: INFO startup-script: SHLVL=2
Feb 20 15:16:19 gceeuw1lin0003 startup-script[1112]: INFO startup-script: _=/usr/bin/printenv

And if I execute printenv command on ssh session, I can see a lot more variables like HOSTNAME, HOME, SHELL…etc.

I'm trying to install a software at startup (proprietary software) but it's failing because of the $HOME variable.

Could not expand the path using $HOME

I tried to setup the HOME varibale in the startup script just before the software installation, but it's failing saying:

invalid command name "wm"

When I try the same installation using an interactive shell, all works fine!
Even better, It works even if I force to rerun the startup scrip from my interactive session using this command:

sudo google_metadata_script_runner --script-type startup --debug

I'm looking for a logical explanation to what's happening? why it's working from the interactive shell and not from the startup script?

Any idea how to fix this?

Thank you in advance!