sync-available: 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/sbin/sync-available - from package: dctrl-tools

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

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