ktmagnetdownloader: 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/ktmagnetdownloader - from package: ktorrent

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

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