euare-usermodkey: command not found

Have You tried accessing the binary with the full path?

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 CentOS possible default full paths are:

/usr/bin/euare-usermodkey - from package: euca2ools

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/euare-usermodkey - from package: euca2ools

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