ecm: 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/ecm - from package: gmp-ecm

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

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