ibstat: 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/ibstat - from package: infiniband-diags

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

On Debian possible default full paths are:

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

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

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