denyhosts-control: 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/denyhosts-control - from package: denyhosts

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

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