ru: 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 CentOS possible default full paths are:

/var/spool/hylafax/bin/dict/ru - from package: hylafax+

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