ibdiagnet: 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/ibdiagnet - from package: ibutils

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

On Debian possible default full paths are:

/usr/bin/ibdiagnet - from package: ibutils

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

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