[FS#988] Procd does not respect a user's groups when using parameter user

[LEDE Bugs]

The following task has a new comment added:

FS#988 - Procd does not respect a user's groups when using parameter user
User who did this - Alexander Lochmann (flipreverse)

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Pls excuse my later response. I didn't get any notification about your answer.
Procd works perfectly with respect to a user's primary group. However, a user might be in more than just his or her primary group.
In my case, the user's foo primary group is staff, and he is also member of the group bar.
However, the procd scripts do not respect those groups....
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More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=988#comment4289