<div dir="ltr">Hi,<div><br></div><div><span style="font-size:12.800000190734863px">is_valid_name() is one of the functions that varies depending on the distributions.</span><br></div><div><span style="font-size:12.800000190734863px"><br></span></div><div><span style="font-size:12.800000190734863px">One historical reason for forbidding periods in user/group names is that it was used by BSD's chown to separate username and groupname.</span></div><div><span style="font-size:12.800000190734863px">I could find this reference: <a href="http://pubs.opengroup.org/onlinepubs/9699919799/utilities/chown.html">http://pubs.opengroup.org/onlinepubs/9699919799/utilities/chown.html</a></span></div><div><span style="font-size:12.800000190734863px"><br></span></div><div><span style="font-size:12.800000190734863px">Also any program could have its own regex and reject / accept usernames (I don't know any standard username regex definition). Although, since much more relaxed policy have been used for a while (for example on Debian: </span><a href="https://github.com/Distrotech/shadow-utils/blob/distrotech-shadow-utils/debian/patches/506_relaxed_usernames">https://github.com/Distrotech/shadow-utils/blob/distrotech-shadow-utils/debian/patches/506_relaxed_usernames</a>) allowing periods should be quite safe.</div><div><br></div><div><span style="font-size:12.800000190734863px">Best Regards,</span></div><div><span style="font-size:12.800000190734863px">-- </span></div><div><span style="font-size:12.800000190734863px">Nekral</span></div></div><div class="gmail_extra"><br><div class="gmail_quote">2016-09-12 13:48 GMT-07:00 Serge E. Hallyn <span dir="ltr"><<a href="mailto:serge@hallyn.com" target="_blank">serge@hallyn.com</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Quoting Alec Larsen (<a href="mailto:notifications@github.com">notifications@github.com</a>):<br>
> Is there a technical reason why dots (`.`) are not allowed in user/group names?<br>
><br>
> And if not, would a PR to allow them be accepted? It seems like a simple enough change to [`is_valid_name` in libmisc/chkname.c](<a href="https://github.com/shadow-maint/shadow/blob/e6b23e1431d8d798bb3c620bc26557ea44a30b98/libmisc/chkname.c#L49" rel="noreferrer" target="_blank">https://<wbr>github.com/shadow-maint/<wbr>shadow/blob/<wbr>e6b23e1431d8d798bb3c620bc26557<wbr>ea44a30b98/libmisc/chkname.c#<wbr>L49</a>).<br>
<br>
Hi,<br>
<br>
this is the kind of thing which seems to me like it should be perfectly<br>
safe, but for which i suspect there is a strong historical (or even<br>
current) reason why it's refused.  I'm cc:ing the mailing list so<br>
hopefully someone less ignorant than I can answer.<br>
<br>
thanks,<br>
-serge<br>
<br>
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</blockquote></div><br></div>