rdate: 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/rdate - from package: rdate

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

On Debian possible default full paths are:

/usr/bin/rdate - from package: rdate

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

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