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

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

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