Why does uucp take group 10?

Question

According to YoLinux, group ID 10 typically belongs to wheel. And on my Arch Linux installation, sure enough there in /etc/group is wheel:10.

However, on my Ubuntu machine instead I'm greeted with uucp. A quick search turns up the Ubuntu man page of uucp, which seems to have a different purpose.

So why does uucp get that group ID? Can I replace it or should I just make wheel a different group ID instead?

Answer 1

The group ID number (GID) is not specifically hard-coded to a particular group. It's designated by the entries in the file /etc/group. On my Fedora 19 system, for example:

$ head -15 /etc/group
root:x:0:
bin:x:1:
daemon:x:2:
sys:x:3:
adm:x:4:logcheck
tty:x:5:
disk:x:6:
lp:x:7:
mem:x:8:
kmem:x:9:
wheel:x:10:saml
cdrom:x:11:
mail:x:12:
man:x:15:
dialout:x:18:

While on an Ubuntu system I have:

$ head -15 /etc/group
root:x:0:
daemon:x:1:
bin:x:2:
sys:x:3:
adm:x:4:manny
tty:x:5:
disk:x:6:
lp:x:7:
mail:x:8:
news:x:9:
uucp:x:10:
man:x:12:
proxy:x:13:
kmem:x:15:
dialout:x:20:

But these are not set in stone. The numbers are what gets stored when files/directories are written to the filesystem. This file is what takes those numbers and display their corresponding name when you use commands such as ls -l.

I would simply make the wheel group another entry in that file, and I'd use a command to add it. You can typically add entries using the addgroup or groupadd commands.

Why is UUCP 10 then?

This ordering is a by-product of when the system was either constructed (**NOTE: I'm talking about when these files were constructed by a particular distro's authors) or when the system went through the process of performing package adds/installs using its package manager (i.e. APT, RPM, pacman, etc.).

References

• 3 UNIX / Linux groupadd Command Examples