AFS stands for Andrew File System and is a distributed file system that was invented at CMU. You have a quota of space and a home directory where you can put your files. You can access these files from any Andrew Unix server or cluster computer on campus.
When you’re using AFS, there’s a system of permissions (called access control lists, or ACLs) regulating who can access your files and what they can do to them. It’s important to know about how to use this system so that you can stop other people from getting access to your homework or other private files.
AFS is set up so that by default, you have a private directory where you can do
~/private. If you don’t change its permissions, you can put all of
your work for your classes in there and no one will be able to access it except
By default, AFS also has a
~/public directory, where you can put things that you
want other people to be able to see. Other users will be able to read files that
you put there (and make copies of them), but not change them, delete them, or
add their own files.
It’s important to be able to control who can access your files on AFS, and
there’s a command called
fs that lets you do this.
For more information on any of the following commands, you can always run
help <command> to get help on that fs subcommand.
You can use
fs la (or fs listacl) to see what the permissions on a directory
are. The output will be an AndrewID or group followed by what they are allowed
to do. For example:
There are several permissions that a user can have for a given directory:
||list files and see basic information about them|
||create (or insert) new files|
||edit (or write) to existing files|
||“lock” files so that no one else can edit them at the same time|
||admin, i.e. change AFS permissions|
You can use
fs sa (or fs setacl) to change the permissions on a directory. The
fs sa <directory> <user ><permissions>
fs sa foo bovik rlidwk
You can use
fs lq (or fs listquota) to see how much of your alloted AFS space
you’re using. For example:
CMU’s AFS has a feature called OldFiles that keeps track of a snapshot of your home folder from the previous day.
Look for it in
~/OldFiles. This is a read-only nightly snapshot of your files
that you can use to copy files you accidentally deleted back to where they
should be. You can
cp files out of it.
~/OldFiles is missing, there is probably still hope! Run the following
commands (substitute your AndrewID for
Now you can look in
~/OldFiles to find your backed up files.