ur: 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/bin/ur - from package: libur-perl

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