mgnokiidev: 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 CentOS possible default full paths are:

/usr/sbin/mgnokiidev - from package: gnokii

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/sbin/mgnokiidev - from package: gnokii-cli

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

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