cereal: 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 Debian possible default full paths are:

/usr/bin/cereal - from package: cereal

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

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