shorewall6-lite: 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:

/sbin/shorewall6-lite - from package: shorewall6-lite

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

Error in other languages:
shorewall6-lite: bevel nie gevind nie
shorewall6-lite: comandă negăsită
shorewall6-lite: comando não encontrado
shorewall6-lite: commande introuvable
shorewall6-lite: command not found
shorewall6-lite: käsku ei ole
shorewall6-lite: không tìm thấy lệnh
shorewall6-lite: komanda nerasta
shorewall6-lite: Kommando nicht gefunden.
shorewall6-lite: kommandot finns inte
shorewall6-lite: komut yok
shorewall6-lite: nie znaleziono polecenia
shorewall6-lite: níor aimsíodh an t-ordú
shorewall6-lite: no se encontró la orden
shorewall6-lite: no s'ha trobat l'ordre
shorewall6-lite: opdracht niet gevonden
shorewall6-lite: parancs nem található
shorewall6-lite: perintah tidak ditemukan
shorewall6-lite: príkaz nenájdený
shorewall6-lite: příkaz nenalezen
shorewall6-lite: команда не найдена
shorewall6-lite: командата не е открита
shorewall6-lite: 命令找不到
shorewall6-lite: コマンドが見つかりません