clamtk: 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/clamtk - from package: clamtk

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

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