On a Mac mini with the following filesystems:

/Volumes/MacintoshHD
/Volumes/MacintoshHD 1
/Volumes/BOOTCAMP
/Volumes/BOOTCAMP 1
/Volumes/Time Machine Backups

running the "[df]" code in "xymonclient-darwin.sh" starting with

FILESYSTEMS=`mount | grep -v nobrowse | awk '{print $3}'`
echo "[df]"
set $FILESYSTEMS
(df -H $1; shift
 while test $# -gt 0
 do
   df -H $1 | tail -1
   shift
 done) | column -t -s " " | sed -e 's!Mounted *on!Mounted on!'

produces this output:

++ mount
++ grep -v nobrowse
++ awk '{print $3}'
+ FILESYSTEMS='/
/Volumes/Time
/Volumes/BOOTCAMP
/Volumes/Macintosh
/Volumes/BOOTCAMP'
+ echo '[df]'
[df]
+ set / /Volumes/Time /Volumes/BOOTCAMP /Volumes/Macintosh /Volumes/BOOTCAMP
+ df -H /
+ column -t -s ' '
+ sed -e 's!Mounted *on!Mounted on!'
+ shift
+ test 4 -gt 0
+ df -H /Volumes/Time
+ tail -1
df: /Volumes/Time: No such file or directory
+ shift
+ test 3 -gt 0
+ df -H /Volumes/BOOTCAMP
+ tail -1
+ shift
+ test 2 -gt 0
+ df -H /Volumes/Macintosh
+ tail -1
df: /Volumes/Macintosh: No such file or directory
+ shift
+ test 1 -gt 0
+ df -H /Volumes/BOOTCAMP
+ tail -1
+ shift
+ test 0 -gt 0
Filesystem    Size  Used  Avail  Capacity  iused      ifree     %iused  Mounted on
/dev/disk0s2  971G  730G  241G   76%       178211272  58934722  75%     /
/dev/disk0s4  28G   24G   4.3G   85%       101211     4246369   2%      /Volumes/BOOTCAMP
/dev/disk0s4  28G   24G   4.3G   85%       101211     4246369   2%      /Volumes/BOOTCAMP

which is obviously quite wrong.

My first proposal is to replace the awk code with

FILESYSTEMS=`mount | grep -v nobrowse | sed -e 's/^.* on \(.*\) [(].*$/\1/g'`

This results in

++ mount
++ grep -v nobrowse
++ sed -e 's/^.* on \(.*\) [(].*$/\1/g'
+ FILESYSTEMS='/
/Volumes/Time Machine Backups
/Volumes/BOOTCAMP
/Volumes/Macintosh HD
/Volumes/BOOTCAMP 1'
+ echo '[df]'
[df]
+ set / /Volumes/Time Machine Backups /Volumes/BOOTCAMP /Volumes/Macintosh HD /Volumes/BOOTCAMP 1

which at least has the correct volume names/strings in it.

Then I would replace this code with something that iterates over each line
of output from 'df', instead of setting FILESYSTEMS all at once from the
entire output.