mkfs: 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/mkfs - from package: util-linux-ng

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

On Debian possible default full paths are:

/sbin/mkfs - from package: util-linux

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

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