monodoc: 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/monodoc - from package: monodoc-browser

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

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