Prefer subprocess over os.system

[kiarn]

Hello,

The use of os.system is deprecated and vulnerable. The use of the module subprocess should be prefered for flexibility, performance and security reasons.

Please see linuxmuster/linuxmuster-linuxclient7#15, as we discussed it ealier with @CodeCrafter912

[dorianim]

This could also be used as an opportunity to use native python code instead of system calls in some places.

[github-actions]

This issue is stale because it has been open for 30 days with no activity.

[dorianim]

This is not done yet and should not be marked stale

[HappyBasher]

72b3c2d