notebook-gtk2: 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/notebook-gtk2 - from package: notebook-gtk2

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

Error in other languages:
notebook-gtk2: bevel nie gevind nie
notebook-gtk2: comandă negăsită
notebook-gtk2: comando não encontrado
notebook-gtk2: commande introuvable
notebook-gtk2: command not found
notebook-gtk2: käsku ei ole
notebook-gtk2: không tìm thấy lệnh
notebook-gtk2: komanda nerasta
notebook-gtk2: Kommando nicht gefunden.
notebook-gtk2: kommandot finns inte
notebook-gtk2: komut yok
notebook-gtk2: nie znaleziono polecenia
notebook-gtk2: níor aimsíodh an t-ordú
notebook-gtk2: no se encontró la orden
notebook-gtk2: no s'ha trobat l'ordre
notebook-gtk2: opdracht niet gevonden
notebook-gtk2: parancs nem található
notebook-gtk2: perintah tidak ditemukan
notebook-gtk2: príkaz nenájdený
notebook-gtk2: příkaz nenalezen
notebook-gtk2: команда не найдена
notebook-gtk2: командата не е открита
notebook-gtk2: 命令找不到
notebook-gtk2: コマンドが見つかりません