
                    For services, we pick up the best solutions provided by github life savers.
                    If google brings you here, you are so lucky! These life savers are angels, they have well solved your problems.
                    So do not waste time scrolling the original issue threads just to dig out solutions... 
                    Here you are, you are welcome. Then, go back to work!
                    

Let's look if it's actually invalid.. Submission type

Bug report

systemd version the issue has been seen with

systemd 232

Used distribution

Linux ubuntu 4.10.0-19-generic #21-Ubuntu SMP Thu Apr 6 17:04:57 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

In case of bug report: Expected behaviour you didn't see

The process started by systemd should be user previlege

In case of bug report: Unexpected behaviour you saw

The process started by systemd was root previlege

In case of bug report: Steps to reproduce the problem
linux user's name : 0day
conf file:   socat.service


and then use systemctl start socat.service to start process

systemd systemd can't handle the process previlege that belongs to user name startswith number, such as 0day

In the mean time I came across a new-to-me command for possibly resolving invalid argument errors:
sudo systemd-analyze verify <unit> 

systemd systemctl - Useless error message - "Failed to enable unit: Invalid Argument"

oneshot services managing their own restart policy (in a bash retry loop or similar) is similar to simple services managing their own restart policies: while it is entirely possible to do this

systemd "Restart" and/or "RestartForceExitStatus" should work with oneshot services, too

FWIW I came up with a simpler minimalistic version of @CrackerJackMack's solution above:


Then 

systemd Access mounted (ip netns ...) network namespaces.

Run brew update this is now fixed by a new Homebrew/brew tag. The latest commit breaks brew services for me 