ibrouters: 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/sbin/ibrouters - from package: infiniband-diags

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

On Debian possible default full paths are:

/usr/sbin/ibrouters - from package: infiniband-diags

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

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