Testing for mount

raypen · 01-30-2005, 06:12 PM

How might I test for the presence of a mounted filesystem
using BASH, Tcl, expect or any other scripting language?

My problem is testing for the presence of a mount and using
if-then-else to mount it if it is not already mounted or umount
if it is.

I assume I would have to somehow read either mtab or /proc/mounts
to determine this, but I am unsure of the syntax to use. I would
assume I would use GREP to extract or read the information but am
unclear on what the comparison syntax would look like.

Any suggestions?

TIA

michaelk · 01-30-2005, 06:23 PM

An example in bash

Code:

test='grep /mnt/cdrom /etc/mtab'
if [ "$test" ]
then
  echo CDROM mounted
else
  echo CDROM not mounted
fi

raypen · 01-30-2005, 11:36 PM

That's kind of what I expected, but I am having trouble with:

test='grep /mnt/cdrom /etc/mtab'

I keep getting the error 'unary operator expected' indicating that
the grep function value is not being assigned to the variable even
though the grep at the command line returns the correct result.
I have tried both single and double quotes and single/double
quotes within double/single quotes all to no avail. I even tried
enclosing 'backtics' within double quotes, but still no go.

I'm sort of at a loss now and need some expert advice.

TIA

Hko · 01-31-2005, 11:47 AM

Quote:

Originally posted by raypen
That's kind of what I expected, but I am having trouble with:

test='grep /mnt/cdrom /etc/mtab'

Yes. The single quotes should have been back-quotes (i.e. ` instead of ' ).

Code:

test=`grep /mnt/cdrom /etc/mtab`

or (bash specific):

Code:

test=$(grep /mnt/cdrom /etc/mtab)

Or do it a different way:

Code:

if grep -q /mnt/cdrom /etc/mtab ; then
    echo CDROM mounted
else
    echo CDROM not mounted
fi

raypen · 01-31-2005, 01:01 PM

Thanks!

test=$(grep /mnt/cdrom /etc/mtab) works the way I want.

Oddly enough test = `grep /mnt/cdrom /etc/mtab`would not
work until I removed the spaces: test=`grep /mnt/cdrom /etc/mtab`

Maybe, one of these days, I'll get it right the first time.

Hko · 01-31-2005, 01:24 PM

Quote:

Originally posted by raypen
Oddly enough test = `grep /mnt/cdrom /etc/mtab`would not
work until I removed the spaces: test=`grep /mnt/cdrom /etc/mtab`

Yes, don't use any whitespace around '=' in bash.

bigearsbilly · 02-01-2005, 08:09 AM

er,
what's wrong with using the mount command?

Hko · 02-01-2005, 11:14 AM

Quote:

Originally posted by bigearsbilly
er,
what's wrong with using the mount command?

Nothing...

Code:

test=$(mount | grep /mnt/cdrom)

should have the same result.