How to Share Files Within a Group
Prior to the early 21st century, when computer security was not so
strict, we were able to share files by sharing the password on a shared
account. New security guidelines forbid the sharing of passwords on any
computer account, and we have moved to a group based model for sharing
files. Between trying to remember yet another username and password (the
old way) and having to remember a couple of new commands (the new way),
you will find that there is little difference in complexity.
User 'accounts' that were once shared will now become 'groups,' and
the people who need access to the files in the target directory will be
made members of the appropriate groups. From now on you will always log in
to the geri system using your own username and password.
Here is how you will access those files that previously were in
shared accounts:
1. Log on to the geri system as usual.
2. Change directory to the group's directory.
3. Do the work you need to do.
4. If you create new files, give the group ownership and the appropriate
permissions.
5. Verify the correct ownership.
6. Change directory back to your own login.
Here is an example of how such a session might look if I wanted to
access files owned by a group named 'p_study'.
1. I run my usual ssh program and log on to the geri system with my
own username and password.
2. 'cd ~p_study' (The tilda is a shortcut to the p_study directory.)
3. 'sas p_study_anal.sas' (Or whatever you need to do.)
4. 'chgrp p_study p_study_anal.log' (Give group ownership to new files)
'chgrp p_study p_study_anal.lis'
'chmod g+w p_study_anal.log' (Give group write permission to new files)
'chmod g+w p_study_anal.lis'
5. Issue the command 'ls -l p_study_anal.l*' to verify the correct ownership.
The output should look something like this:
-rw-rw-r-- 1 owner p_study 512 Jul 9 2004 p_study_anal.log
-rw-rw-r-- 1 owner p_study 512 Jul 9 2004 p_study_anal.lis
6. 'cd' (Go back to my login directory)
