Hello,
I'm trying to write a bash script for a back up job. Unfortunately I'm not getting
anywhere.
>I need to mount a file system only if the filesystem is
>_not_ already mounted.
>
>I'm thinking of it like this:
Ok, I've been reading documentation and wrote a test script. I've so far managed to
make it like this:
#!/bin/bash
if [ -n `mount |grep "/mnt/root/cschomeserver/e"` ] #if it's already mounted don't
mount it
then PREMOUNTED='YES' && echo "is mounted" #If it's already mounted set a var
else echo "mount /mnt/root/cschomeserver/e is not mounted" #if it's not mounted,
mount it.
fi
echo $PREMOUNTED
Unfortunately it seems that -n is exactly the opposite of what I need because the
output is backwards. Additionally, it was working backwards but without error a minute
ago and now it's giving that "too many arguments" thing - I'm not sure what's changed,
I tried undoing my (very small) edits to the file and it's still erroring even after
the un-do so I'm not sure what happened.
When it really is mounted I get the following output from that script:
fluorite:~ # ./test.sh
./test.sh: [: too many arguments
mount /mnt/root/cschomeserver/e is not mounted
Which is backwards - it is mounted. As you can see PREMOUNTED doesn't get set either -
again, that's backwards.
Then when it really isn't mounted the script _does_ set the var:
fluorite:~ # umount /mnt/root/cschomeserver/e/
fluorite:~ # ./test.sh
YES
So, can someone tell me what the opposite of -n is? According to the man page it's -z
but that's acting the same as -n (weird) I can't figure it out. I've tried -n, -z and
a host of other options I see in the man page and none of it's working and it's
backwards both ways.
Also can anyone explain the "too many arguments" part - are you not allowed to run a
command inside [] for output?
I'm also testing it with the interactive shell, such as the following variation:
fluorite:~ # if test -n $( `mount |grep "/mnt/root/cschomeserver/e"` ) ; then
PREMOUNTED="YES" && echo $PREMOUNTED ; else echo "no" ; fi
YES
Unfortunately this (and test -z) is always returning "YES" so something's still quite
wrong.
Obviously I do not understand how to properly get a yes/no value out of the string
returned from a nested command. If someone could explain even that much I'd appreciate
it.
TIA
----------------------------------------------------
Jonathan Wilson
System Administrator
Cedar Creek Software http://www.cedarcreeksoftware.com
Central Texas IT http://www.centraltexasit.com
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