tuned: 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:

/usr/sbin/tuned - from package: tuned

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

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