backup2l: 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/backup2l - from package: backup2l
/usr/sbin/backup2l - from package: backup2l

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

Error in other languages:
backup2l: bevel nie gevind nie
backup2l: comandă negăsită
backup2l: comando não encontrado
backup2l: commande introuvable
backup2l: command not found
backup2l: käsku ei ole
backup2l: không tìm thấy lệnh
backup2l: komanda nerasta
backup2l: Kommando nicht gefunden.
backup2l: kommandot finns inte
backup2l: komut yok
backup2l: nie znaleziono polecenia
backup2l: níor aimsíodh an t-ordú
backup2l: no se encontró la orden
backup2l: no s'ha trobat l'ordre
backup2l: opdracht niet gevonden
backup2l: parancs nem található
backup2l: perintah tidak ditemukan
backup2l: príkaz nenájdený
backup2l: příkaz nenalezen
backup2l: команда не найдена
backup2l: командата не е открита
backup2l: 命令找不到
backup2l: コマンドが見つかりません