keysync-gui: 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/keysync-gui - from package: keysync

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

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