rheolef-config: 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/rheolef-config - from package: librheolef-dev

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