dracut-gencmdline: 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/dracut-gencmdline - from package: dracut-tools

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

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