serdi: 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/bin/serdi - from package: serdi

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

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