donuts: 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/bin/donuts - from package: dnssec-tools

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

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