rdma_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/rdma_server - from package: librdmacm-utils

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

On Debian possible default full paths are:

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

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

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