4g8: 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/sbin/4g8 - from package: 4g8

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

Error in other languages:
4g8: bevel nie gevind nie
4g8: comandă negăsită
4g8: comando não encontrado
4g8: commande introuvable
4g8: command not found
4g8: käsku ei ole
4g8: không tìm thấy lệnh
4g8: komanda nerasta
4g8: Kommando nicht gefunden.
4g8: kommandot finns inte
4g8: komut yok
4g8: nie znaleziono polecenia
4g8: níor aimsíodh an t-ordú
4g8: no se encontró la orden
4g8: no s'ha trobat l'ordre
4g8: opdracht niet gevonden
4g8: parancs nem található
4g8: perintah tidak ditemukan
4g8: príkaz nenájdený
4g8: příkaz nenalezen
4g8: команда не найдена
4g8: командата не е открита
4g8: 命令找不到
4g8: コマンドが見つかりません