xymonfetch: 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/xymonfetch - from package: xymon

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

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