file systems

[gzf at gbr.msd.ray.com (Jerry Feldman {75562})]

John Malloy wrote:
> 
> What is the syntax to "unlink" the file system?
You do not unlink a file system. You unlink a file. The command is rm.
In Unix, files are an entry in the inode array. The file name is an entry in
directory which points to the inode entry. A file can have from 1 to many
links (now referred to as hard links). 
Example:
create a file in the current directory:
touch malloy.
Make a link:
ln malloy jmalloy
[src/hpbenches] ls -l | grep malloy
-rw-rw-r--   2 gzf        4390             0 Jul 22 10:57 jmalloy
-rw-rw-r--   2 gzf        4390             0 Jul 22 10:57 malloy
Note the file has 2 links.
rm jmalloy
ls -l | grep malloy
[src/hpbenches] ls -l | grep malloy
-rw-rw-r--   1 gzf        4390             0 Jul 22 10:57 malloy
Now the file has 1 link. Internally, the inode has a use or reference count. 
Now you rm malloy and the file will be gone. You can actually check the
inode table if you want. 

A file system may be mounted on any subdirectory. 
Let's say you have a file system on a floppy disk:
mkdir malloy
mount /dev/fd0 malloy
Now, the floppy disk will be mounted on the directory, malloy. 
Now let's remove it:
umount malloy
rmdir malloy

The rmdir command is the way you remove directories. You can also use the
recursive and force option to rm.
The umount command will effectively detach a file system from it's mount
point, whcih can be any directory. 


-- 
Jerry Feldman (HP On-Site Consultant) http://gbrweb.msd.ray.com/~gzf/
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