ilasm: 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/ilasm - from package: mono-devel

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

On Debian possible default full paths are:

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

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

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