euare-usermodcert: 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-usermodcert - from package: euca2ools

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

On Debian possible default full paths are:

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

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