lxc-start-ephemeral: 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/lxc-start-ephemeral - from package: lxc

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

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