xtuple: 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/xtuple - from package: postbooks

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

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