[NTLUG:Discuss] force group ownership

[Paul Ingendorf]

Your have three bit's for each of the following
The user
The Group
Everyone.
They are read write execute. If you look at how these are arranged you have the following in binary.
Read 100
Write	010
Execute 001
Read = 4 in decimal.
Write = 2 in decimal.
Execute = 1 in decimal.

Now you can combine each of the above in various combinations in which you basically turn on or off a bit in the 3 digit binary number for the read write execute you concatenate a decimal value for user group and everyone and end up with the following.  For a user and group with read write permissions and everyone with read permissions.


READ WRITE EXEC READ WRITE EXEC READ WRITE EXEC
  1     1    0    1     1    0    1     0    0
Or if you convert each 3 bit group to decimal you get

664

Now to umask this subtract each numeral from 7 so 6 from 7 then 6 from 7 and last 4 from 7.  Or if your the engineering type your simply performing a 1's compliment on each 3bit grouping then doing a binary to decimal conversion on it.

Either way your umask is now 113.

This gives read write to the user who created it as well as the group and read permission to everyone else.

Sorry for the long answers but you don't see many questions on this and it is very important to understand how permissions work in order to maintain a secure setup and still give your users the flexibility they need to get their work done.

-----Original Message-----
From: discuss-admin at ntlug.org [mailto:discuss-admin at ntlug.org]On Behalf
Of Bobby Wrenn
Sent: Friday, February 01, 2002 11:40 AM
To: discuss at ntlug.org
Subject: Re: [NTLUG:Discuss] force group ownership


So far so good!

Access for the planning group is working. What is the best way to allow
all users on the LAN read only access to the planning files?

My thought was to create a guest user with this as the home directory
and give that user read only access.

Is there another (better) way?

Thanks again,
Bobby

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