OgreMeshUpgrader: 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/OgreMeshUpgrader - from package: ogre-1.8-tools
/usr/bin/OgreMeshUpgrader - from package: ogre-1.9-tools

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

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