4294967295 is just (unsigned long) -1. -1 means that loginuid was not set. This is normal behavior for processes that were not spawned by any login process (e.g. for daemons). loginuid is -1 by default; pam_loginuid module changes it to your user id whenever you login (in a tty/in DM/via ssh), and this value is preserved by child processes.
可惜的是proc.txt并未对此文件有过说明
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