Logwatch disk space report

[Paul Howarth]

Kanwar Ranbir Sandhu wrote:
> Hi Everyone,
> 
> [I originally sent this using the wrong email account.  I'm not sure if
> the first email will make it through, so here it is again]
> 
> So, I wanted to figure out why the logwatch report mangles the disk
> space usage report.  Here's what I receive for one of my servers:
> 
> /dev/mapper/VolGroup00-LogVol00
> /dev/hda1             101M   15M   80M  16% /boot
> /dev/mapper/VolGroup00-home
> /dev/mapper/VolGroup00-tmp
> /dev/mapper/VolGroup00-usr
> /dev/mapper/VolGroup00-var
> 
> That's obviously incomplete.  If I just run df -h, I get this:
> 
> /dev/mapper/VolGroup00-LogVol00
>                       496M  172M  299M  37% /
> /dev/hda1             101M   15M   80M  16% /boot
> none                  173M     0  173M   0% /dev/shm
> /dev/mapper/VolGroup00-home
>                       434M   34M  379M   9% /home
> /dev/mapper/VolGroup00-tmp
>                       496M   13M  459M   3% /tmp
> /dev/mapper/VolGroup00-usr
>                       2.9G  830M  2.0G  30% /usr
> /dev/mapper/VolGroup00-var
>                       992M  234M  708M  25% /var
> 
> Much better (except for the ugly output).
> 
> Anyway, here's the line in the script that logwatch fires up to create
> the disk usage report:
> 
> df -h | grep '^/dev/'
> 
> It appears that if the path to the device being is sufficiently long
> enough, the disk usage for that device isn't printed.  I've tried the
> same command on my laptop (also setup with LVM), and the same thing
> happens:
> 
> /dev/mapper/vg00-root
> /dev/hda1              99M   12M   82M  13% /boot
> /dev/mapper/vg00-home
> /dev/mapper/vg00-opt 1008M   34M  924M   4% /opt
> /dev/mapper/vg00-tmp 1008M   34M  924M   4% /tmp
> /dev/mapper/vg00-usr  3.9G  2.6G  1.1G  71% /usr
> /dev/mapper/vg00-local
> /dev/mapper/vg00-var 1008M  415M  542M  44% /var
> 
> Notice that /dev/mapper/vg00-home and /dev/mapper/vg00-local are both
> empty.
> 
> Questions:
> 
> 1. Why the need to grep for /dev?  df -h alone does the job well.
> 2. What's the solution?
>         a. change the script to use df -h ?
>         b. use shorter VG labels?
>         c. something else entirely?

This one's been bugging me a little too, and your message prompted me to 
have a look at it.

Try editing /etc/log.d/scripts/services/zz-disk_space and changing:

grep '^/dev/'

to:

awk '/^\/dev/ { print; if (NF < 6) { getline; print } }'

I'd guess that the search for /dev/ is there to select only local 
filesystems, and it's not using the "-l" option so as to avoid the 
pseudo-filesystems that you get with that option.

Paul.