ewarn: 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:

/lib/rc/bin/ewarn - from package: openrc

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

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