keyctl: 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:

/bin/keyctl - from package: keyutils

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

On Debian possible default full paths are:

/bin/keyctl - from package: keyutils

You may install the required package with command apt-get install {package}

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