jday: 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/jday - from package: jday

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

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