gappletviewer: 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/gappletviewer - from package: gcj-jdk

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

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