mount and umount

[Robert Meyer]

When you unmount a device, the underlying directory becomes available again. 
Remember that you mount a filesystem on an existing directory.

Cheers!

Bob
--- Asheville Joe <josephj at main.nc.us> wrote:
> I have a removeable ide hard disk as hdb1.  I want to write a script to
> access it for backup (a copy of my fstab is included below.  I wanted to 
> test if it was mounted, and, if not, mount it.  To try it out, I went 
> into an Xterm.
> I su'd and mounted it -
> mount /dev/hdb1 /mount/portable.  I  did a cd /mnt/portable and wrote a
> small junk file to it and that worked.  So far so good.  Then, I did a
> cd .. and umount /dev/hdb1.
> I tried that again and it told it was not mounted (as expected).  BUT, I
> then did an ls /mnt/portable and it still worked!  I even copied another
> small junk file to it (although I had to su for it to work, which I 
> don't understand).
> 
> I thought that when I unmounted the device, trying to access, let alone
> write to /mnt/portable would fail and generate an error.  It didn't!
> 
> What don't I understand (about this in particular :) )?
> 
> How do you test to see if a device is mounted (or accessible?) ?
> 
> Joe
> 
> /etc/fstab:
> 
> /dev/hda7 / ext3 defaults 1 1
> /dev/hda6 /boot ext2 defaults 1 2
> none /dev/pts devpts mode=0620 0 0
> /dev/hda9 /home ext3 defaults 1 2
> none /mnt/cdrom supermount
> dev=/dev/scd0,fs=auto,ro,--,iocharset=iso8859-1,codepage=850,umask=0 0 0
> /dev/hda1 /mnt/dos_hda1 vfat
> iocharset=iso8859-1,codepage=850,umask=0,defaults 0 0
> /dev/hda5 /mnt/dos_hda5 vfat
> iocharset=iso8859-1,codepage=850,umask=0,defaults 0 0
> none /mnt/floppy supermount
> dev=/dev/fd0,fs=auto,--,iocharset=iso8859-1,sync,codepage=850,umask=0 0 0
> /dev/hdb1 /mnt/portable ext3 rw,user,noauto,exec,suid 0 0
> none /proc proc defaults 0 0
> /dev/hda8 swap swap defaults 0 0
> ----------------------------------
> "I can assure you the flying saucers, given that they exist, are not
> constructed by any power on earth." --Harry S. Truman; White House Press
> Conference, Washington DC, April 4, 1950.
> 
> 
> 
> 
> 


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