sasl2-sample-server: 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/sasl2-sample-server - from package: cyrus-sasl-devel

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

Error in other languages:
sasl2-sample-server: bevel nie gevind nie
sasl2-sample-server: comandă negăsită
sasl2-sample-server: comando não encontrado
sasl2-sample-server: commande introuvable
sasl2-sample-server: command not found
sasl2-sample-server: käsku ei ole
sasl2-sample-server: không tìm thấy lệnh
sasl2-sample-server: komanda nerasta
sasl2-sample-server: Kommando nicht gefunden.
sasl2-sample-server: kommandot finns inte
sasl2-sample-server: komut yok
sasl2-sample-server: nie znaleziono polecenia
sasl2-sample-server: níor aimsíodh an t-ordú
sasl2-sample-server: no se encontró la orden
sasl2-sample-server: no s'ha trobat l'ordre
sasl2-sample-server: opdracht niet gevonden
sasl2-sample-server: parancs nem található
sasl2-sample-server: perintah tidak ditemukan
sasl2-sample-server: príkaz nenájdený
sasl2-sample-server: příkaz nenalezen
sasl2-sample-server: команда не найдена
sasl2-sample-server: командата не е открита
sasl2-sample-server: 命令找不到
sasl2-sample-server: コマンドが見つかりません