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

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

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