pethtool: 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/pethtool - from package: python-ethtool

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

On Debian possible default full paths are:

/usr/sbin/pethtool - from package: python-ethtool

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

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