rping: 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/rping - from package: librdmacm-utils

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

On Debian possible default full paths are:

/usr/bin/rping - from package: rdmacm-utils

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

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