xymond_rrd: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/lib/xymon/server/bin/xymond_rrd - from package: xymon

You may install the required package with command apt-get install {package}

Error in other languages:
xymond_rrd: bevel nie gevind nie
xymond_rrd: comandă negăsită
xymond_rrd: comando não encontrado
xymond_rrd: commande introuvable
xymond_rrd: command not found
xymond_rrd: käsku ei ole
xymond_rrd: không tìm thấy lệnh
xymond_rrd: komanda nerasta
xymond_rrd: Kommando nicht gefunden.
xymond_rrd: kommandot finns inte
xymond_rrd: komut yok
xymond_rrd: nie znaleziono polecenia
xymond_rrd: níor aimsíodh an t-ordú
xymond_rrd: no se encontró la orden
xymond_rrd: no s'ha trobat l'ordre
xymond_rrd: opdracht niet gevonden
xymond_rrd: parancs nem található
xymond_rrd: perintah tidak ditemukan
xymond_rrd: príkaz nenájdený
xymond_rrd: příkaz nenalezen
xymond_rrd: команда не найдена
xymond_rrd: командата не е открита
xymond_rrd: 命令找不到
xymond_rrd: コマンドが見つかりません