Re: Checking for a mount in a shell script (Was: Re: Preparing for Debian 13)

[Lee <ler762@gmail.com>]

On Sun, May 18, 2025 at 8:03 PM Greg Wooledge wrote:
>
> On Sun, May 18, 2025 at 19:51:04 -0400, Lee wrote:
> > On Sun, May 18, 2025 at 4:51 PM Andy Smith wrote:
> > >
> > > Hi,
> > >
> > > On Sun, May 18, 2025 at 12:47:25PM -0400, Default User wrote:
> > > > Since I know almost no shell scripting, the rsync usb drive A
> > > > to usb drive B copy is done with a simple bash script consisting
> > > > only of the rsync backup command, with options and parameters, but
> > > > without any code to verify that usb drive B is attached.
> > >
> > > If your backup script is a bash script then all you need do is put
> > > something like:
> > >
> > > if ! findmnt /mnt/usb-drive-b; then
> >
> > just  out of curiosity.. why "findmnt" instead of
> > if [ ! -d /mnt/usb-drive-b ]; then
>
> It will always be a directory.  The question is whether there's a file
> system mounted on it.

I have a script to do a quick rsync backup to usb and ran into the
same problem.. oops! I forgot to insert the usb stick.
After a bit of experimentation I found that checking for the existence
of the directory was good enuf:

-----------------
DEST="/media/lee/TravelDrive/deb-spot"

if [ ! -d "$DEST" ]; then
   echo "$DEST does not exist!!"  >&2
   exit 1
fi
  <.. snip ..>
-----------------

$ ./syncusb
/media/lee/TravelDrive/deb-spot does not exist!!

-----------------

Is "/media/USERID" magic or what?
In other words, why will /mnt/usb-drive-b always be a directory but
/media/USERID doesn't exist unless the usb drive is mounted?

Thanks
Lee