kswarm.kss: 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/kswarm.kss - from package: kscreensaver

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

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