rdswap: 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/rdswap - from package: rdtool

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

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