xbstream: 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/xbstream - from package: percona-xtrabackup

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

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