combostatus: 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/combostatus - from package: xymon

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

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