hibernate-ram: 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/sbin/hibernate-ram - from package: hibernate

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

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