rsyncd-enable: command not found

Have You tried accessing the binary with the full path?

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/share/solr/bin/rsyncd-enable - from package: solr-common

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