openxenmanager: command not found

Have You tried accessing the binary with the full path?

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

[root@server ~]# echo $PATH

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/bin/openxenmanager - from package: openxenmanager

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