drpmsync: 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/drpmsync - from package: drpmsync

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

On Debian possible default full paths are:

/usr/bin/drpmsync - from package: deltarpm

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

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