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

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

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