urxvtd: 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/urxvtd - from package: rxvt-unicode

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

On Debian possible default full paths are:

/usr/bin/urxvtd - from package: rxvt-unicode-256color
/usr/bin/urxvtd - from package: rxvt-unicode-lite
/usr/bin/urxvtd - from package: rxvt-unicode

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

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