diagperm: 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 Debian possible default full paths are:

/usr/sbin/diagperm - from package: netdiag

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

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