How do groups work on Linux?

One of the most useful group-related tricks (introduced in BSD Unix, I believe) is the setgid bit on a directory. If this is set, new files and subdirectories created within the directory will have the same group as the directory, rather than the group of the process that created them.

The book she mentions, "The Linux Programming Interface," sounds pretty useful, but it's seven years old at this point. Does anyone know how much has changed or if there's a new version coming any time soon? Seems like it's worth $70 but the age has me concerned. I'm sure the basics, like the things this article is about, haven't changed, but I bet all the stuff around cgroups would be useful for how setgid works with a process.

I absolutely love Julia Evan's writing. I find her articles / zines to cover interesting and useful technical topics while remaining _extremely_ accessible to me (especially when I was a student)! I really admire her ability to present technical topics in plain language.

Ohh, so THAT's why I have to log out and back in to have my group changes take effect. That, along with having to start a new shell to pick up new env vars from ~/.profile, are my two biggest annoyances with the Linux process model. Reminds me a bit of the Windows 98 days when you had to restart to change your IP address. I really wish someone would sit down and figure out how to propagate group and environment changes to already running processes and implement them.

Some highlighted words do not appear using Firefox 57 on my Ubuntu 16.04.3, like the word &quot;julia&quot; at the third line. It&#x27;s OK with Chromium.<p>EDIT: Seems a Firefox related bug, i noticed this strange behavior with other websites inc. Stack Overflow since then. Will investigate asap.

Regarding setuid, this is why when you run programs like ping(8) it doesn&#x27;t require root access to open a raw socket. ping&#x27;s setuid is set so upon execution it executes as root since ping is owned by root and then calls setuid(getuid()) to run as the intended user.

Also &quot;newgrp&quot; can be used for join &quot;new&quot; groups without re-login.

&quot;dr--r--r-- 1 bork awesome 6872 Sep 24 11:09 file.txt&quot;<p>This doesn&#x27;t make sense.