synaptiks: 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/synaptiks - from package: kde-config-touchpad

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

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