XrdCnsd: 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/XrdCnsd - from package: xrootd-server

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

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