mgp2ps: command not found

Have You tried accessing the binary with the full path?

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/mgp2ps - from package: mgp

You may install the required package with command apt-get install {package}
Error in other languages:
mgp2ps: bevel nie gevind nie
mgp2ps: comandă negăsită
mgp2ps: comando não encontrado
mgp2ps: commande introuvable
mgp2ps: command not found
mgp2ps: käsku ei ole
mgp2ps: không tìm thấy lệnh
mgp2ps: komanda nerasta
mgp2ps: Kommando nicht gefunden.
mgp2ps: kommandot finns inte
mgp2ps: komut yok
mgp2ps: nie znaleziono polecenia
mgp2ps: níor aimsíodh an t-ordú
mgp2ps: no se encontró la orden
mgp2ps: no s'ha trobat l'ordre
mgp2ps: opdracht niet gevonden
mgp2ps: parancs nem található
mgp2ps: perintah tidak ditemukan
mgp2ps: príkaz nenájdený
mgp2ps: příkaz nenalezen
mgp2ps: команда не найдена
mgp2ps: командата не е открита
mgp2ps: 命令找不到
mgp2ps: コマンドが見つかりません