mkfs.xfs: 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.xfs - from package: xfsprogs

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

On Debian possible default full paths are:

/sbin/mkfs.xfs - from package: xfsprogs

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

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