rsyncd-stop: 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-stop - from package: solr-common

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