How to grant the file privilege

[IPOz]

Hi,friends
I have a file called test.c as below:
#ls -l
-rw-r----- 1 myname mygroup 8352 Aug 14 14:57 test.c

Now i want to grant the user B read only this file and user C write only it.How can i get it?
if
#usermod -G mygoup B
the user B can read test.c only.But i donot know how to make user C write test.c only.

Any help is appreciated!
IPO_z@cmmail.com
Garbage in,Garbage out

 

[zallen]

Maybe it is difficult to implement your goal.I think the privilege bits are not enough

Do you think about the PAM?

Regards! zallen@cmmail.com
Long live of freedom!

 

[marsd]

Owner read only user
write only group member
------------------------
chmod 420 file name
chown reader file name

(make a writeonly group for the files and place
the second user in it.)

chgrp writers file name

This can be clunky to learn but is very flexible.

ex:
All my users from proofreading use the single user
account proofer.
All my programmers are members of the oops group.

 

[zallen]

marsd,
I understand what you said. But is it possible to implement it without changing the ownership?
In windows i only need to share the directory in which the file lives.I can easily control who can read the file and who can write the file.

Regard! zallen@cmmail.com
Long live of freedom!

 

[marsd]

You are talking about "inherited permissions."..No
this is not the way permissions work I am afraid.
No, I really don't see a way around this..unless
you would like to wrap the whole thing in a custom
shell script-which might be a little safer than having
one group have blind writes...
Maybe there is a PAM plugin for this...