ibv_ud_pingpong: 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/ibv_ud_pingpong - from package: libibverbs-utils

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

On Debian possible default full paths are:

/usr/bin/ibv_ud_pingpong - from package: ibverbs-utils

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

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