xmlwidget: 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
/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/xmlwidget - from package: qtoctave

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