riostream: 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/riostream - from package: librdmacm-utils

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

On Debian possible default full paths are:

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

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

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