sgen: 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/sgen - from package: mono-devel

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

On Debian possible default full paths are:

/usr/bin/sgen - from package: mono-devel

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

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