xringd: 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/sbin/xringd - from package: xringd

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