Safe to use non-unique UID ?

nico562 · 06-19-2006, 01:00 AM

Hi, i am manageing a system where we have a whole bunch of users.
Their only purpose on the system, is to logon through ssh, and manage their own "html" folder, which contains their website.

1) i was wondering if it could be okey to use a non-unique UID, for future users - in this situation?
2) what are the advantages and disadvantages of useing a non-unique UID?

3) currently, their connect trough a zsh, but would it bear any risk to use (fx.) Bash instead?
4) what is generally the reason for the different shell use?

big thanks

/Nicholas

acid_kewpie · 06-19-2006, 01:18 AM

1) why on earth would you want to??
2) there are no advantages to trying to use the same UID, it's sick and wrong.
3) bash is fine
4) because different shells do different things

nico562 · 06-19-2006, 01:43 AM

Quote:

Originally Posted by acid_kewpie

1) why on earth would you want to??
2) there are no advantages to trying to use the same UID, it's sick and wrong.
3) bash is fine
4) because different shells do different things

Because while i was makeing a script for adding users, i stumbled over this function (useradd -o), and saw it could ease my work tremendously!

please, i would like to know why its "stick and wrong", i cant really use that response to much - other than you think negative about it - but that doesnt give me any insite on why?

acid_kewpie · 06-19-2006, 01:48 AM

files are not owned by usernames, they are owned by uid's. if you have two users with the same uid they will be the same person when it comes to file access. they will be bale to edit each others files as if they were there own, without any way of stopping it. I really don't see why your work would be eased by this at all. uid's are assigned on a sequential basis, you have no reason to even know what a users uid ever is.

nico562 · 06-19-2006, 01:54 AM

Quote:

Originally Posted by acid_kewpie

files are not owned by usernames, they are owned by uid's. if you have two users with the same uid they will be the same person when it comes to file access. they will be bale to edit each others files as if they were there own, without any way of stopping it. I really don't see why your work would be eased by this at all. uid's are assigned on a sequential basis, you have no reason to even know what a users uid ever is.

I see, i feel almost stupid now overseeing that.

Tell me more about this "sequential basis", as far a i know, one has to set the UID oneself?
..which is what im finding problematic in my perl script, - that is, generating a nice controlled line of numbers for the UID's.

acid_kewpie · 06-19-2006, 02:51 AM

useradd will just assign the next uid in the range it is configured to do so. normally this is from 500 upwards. only time i've ever manually picked a uid is when i want to have two identical users accessing a common NFS share etc...

nico562 · 06-19-2006, 07:49 AM

Quote:

Originally Posted by acid_kewpie

useradd will just assign the next uid in the range it is configured to do so. normally this is from 500 upwards. only time i've ever manually picked a uid is when i want to have two identical users accessing a common NFS share etc...

hmm, isnt it possible to enter the range oneself? ive tried looking for it - no luck

/EDIT;

Nevermind, that was a stupid question. Found it in the Man pages (-k option).

homey · 06-19-2006, 08:47 AM

I never felt the need to change this but, on my FC5 box, it looks like you could adjust the range in /etc/login.defs

Code:

# Min/max values for automatic uid selection in useradd
#
UID_MIN			  500
UID_MAX			60000

nico562 · 06-19-2006, 02:41 PM

Quote:

Originally Posted by homey

I never felt the need to change this but, on my FC5 box, it looks like you could adjust the range in /etc/login.defs

Code:

# Min/max values for automatic uid selection in useradd
#
UID_MIN			  500
UID_MAX			60000

well ill' be changeing them, for manageing purposes. i wont go into detail about it