mglconv: 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/mglconv - from package: mathgl

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

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