ibswitches: 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/ibswitches - from package: infiniband-diags

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

On Debian possible default full paths are:

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

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

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