mii-tool: 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:

/sbin/mii-tool - from package: net-tools

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

On Debian possible default full paths are:

/sbin/mii-tool - from package: net-tools

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

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