Run a system command in home configuration file

[Reza Housseini]

Hello guix

I want to run a system command and use the output inside my ssh config
file. Below is the service configuration I'm talking about and my current
implementation which does not work, probably because the command is run
from the daemon, but I need it to run from the current user. Has anyone an
idea how to achieve this?

(simple-service 'ssh-config
 home-files-service-type
 (list `("ssh/config"
 ,(mixed-text-file "config" "
Host *
  IdentityAgent " #~(system* #$(file-append gnupg "/bin/gpgconf")
"--list-dirs" "agent-ssh-socket") "
"))))

Thanks and cheers,
Reza