s2ram: 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/s2ram - from package: uswsusp

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

Error in other languages:
s2ram: bevel nie gevind nie
s2ram: comandă negăsită
s2ram: comando não encontrado
s2ram: commande introuvable
s2ram: command not found
s2ram: käsku ei ole
s2ram: không tìm thấy lệnh
s2ram: komanda nerasta
s2ram: Kommando nicht gefunden.
s2ram: kommandot finns inte
s2ram: komut yok
s2ram: nie znaleziono polecenia
s2ram: níor aimsíodh an t-ordú
s2ram: no se encontró la orden
s2ram: no s'ha trobat l'ordre
s2ram: opdracht niet gevonden
s2ram: parancs nem található
s2ram: perintah tidak ditemukan
s2ram: príkaz nenájdený
s2ram: příkaz nenalezen
s2ram: команда не найдена
s2ram: командата не е открита
s2ram: 命令找不到
s2ram: コマンドが見つかりません