vendstat: 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/vendstat - from package: infiniband-diags

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

On Debian possible default full paths are:

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

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

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