xsddiagram: 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/xsddiagram - from package: xsddiagram

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

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