xen-list-images: 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/bin/xen-list-images - from package: xen-tools

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

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