faillock: 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/faillock - from package: pam

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

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