osgviewer: 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/osgviewer - from package: openscenegraph

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

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