xenstore-write: 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/sbin/xenstore-write - from package: xenstore-utils

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