osgearth_overlayviewer: 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/osgearth_overlayviewer - from package: osgearth

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

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