UID/GID < 100

[F Verschuren]

hi,
Can some one tell me what aditional rights I have if my user ID and or group ID is 50 < 100
I know that some comandas does not see the groups < 100.
#listusers -g users
'users' is not a user group


And is someone knows also for AIX ?
The listusers command is working on AIX for all groups and users so if somebody knows someting that the users whit UID/GID 50-99 gain on AIX please also post it?

[Pete Randall]

There are no additional rights or privileges associated with these UIDs. UIDs less than 100 are traditionally reserved for system related accounts: root, bin, sys, lp and the like.


Pete

[TTr]

You may have discover a bug or limitation (aka feature) of the listusers command. The man page does mention that the UID must be < 100 but no mention of the group limitation. Other than the already assigned system UIDs and GIDs, any unused ID numbers can be treated as any regular user or group ID. Typically we do not use these because the system may have to use them with the new services that come into play with every new version of the OS.

[James R. Ferguson]

Hi:

See the manpages for 'passwd(4)':

"It is suggested that the range 0-99 not be used for user and group IDs so that IDs that might be assigned for system software do not
conflict."

Regards!

...JRF...

[F Verschuren]

if I do a man listusers I see:

A user login has a UID of 100 or greater.

Also the listusers comands gaves the same error on sun
I have heard there was somting that a user <100 can do more prio/nice settings in the past, but I am not able to recreate,


also find a man page on internet showing:
User ID (uid) 18 is reserved for the BASIC Language operating system.
These are operating systems for Series 300 and 400 computers that can
co-exist with HP-UX on the same disk. Using these uids for other
purposes may inhibit file transfer and sharing.

but do that I only have 9000 systems I can not test it.
Still searching,

[Steve Lewis · Accepted solution]

If the ids under 100 are reserved for the o/s utilities then why do HP use 101, 102 and so on for new o/s utilities and leave the lower numbers unused? I am talking about things like hpsmh and sfmdb, iwww, owww, tftp, sshd etc.

All around the world people like me working on PA-RISC to Itanium replacement (coupled with HP-UX 11.00 to 11.v2/3 upgrades) where the user ids in the low 100s on the old systems were used by real users, but now have been taken by HP-UX during the installation. This is causing us all a lot of painstaking work, adjusting all the user ids from old system to new when files and home directories are copied over. It also means that decisions have to be made whether or not to keep the same Ids as the old systems (adjusting the new o/s) or to adjust everyone's ID on the new systems so that everyone has to have a new user id, which causes extra work if you have to restore files from backup.

It would have been much easier for the rest of us for HP to allocate itself numbers from 99 downwards as the man page suggests and not simply do a useradd for each package as it gets installed. I can see why they did it, but its a real pain.

The same applies to Group Ids.