mglview: 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/mglview - from package: mathgl

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

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