mkdosfs: 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/mkdosfs - from package: dosfstools

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

On Debian possible default full paths are:

/sbin/mkdosfs - from package: dosfstools

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

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