elki: 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/elki - from package: elki

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

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