ubuntu-ec2-run: 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/ubuntu-ec2-run - from package: cloud-utils

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

Error in other languages:
ubuntu-ec2-run: bevel nie gevind nie
ubuntu-ec2-run: comandă negăsită
ubuntu-ec2-run: comando não encontrado
ubuntu-ec2-run: commande introuvable
ubuntu-ec2-run: command not found
ubuntu-ec2-run: käsku ei ole
ubuntu-ec2-run: không tìm thấy lệnh
ubuntu-ec2-run: komanda nerasta
ubuntu-ec2-run: Kommando nicht gefunden.
ubuntu-ec2-run: kommandot finns inte
ubuntu-ec2-run: komut yok
ubuntu-ec2-run: nie znaleziono polecenia
ubuntu-ec2-run: níor aimsíodh an t-ordú
ubuntu-ec2-run: no se encontró la orden
ubuntu-ec2-run: no s'ha trobat l'ordre
ubuntu-ec2-run: opdracht niet gevonden
ubuntu-ec2-run: parancs nem található
ubuntu-ec2-run: perintah tidak ditemukan
ubuntu-ec2-run: príkaz nenájdený
ubuntu-ec2-run: příkaz nenalezen
ubuntu-ec2-run: команда не найдена
ubuntu-ec2-run: командата не е открита
ubuntu-ec2-run: 命令找不到
ubuntu-ec2-run: コマンドが見つかりません