root-config: 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 CentOS possible default full paths are:

/usr/bin/root-config - from package: root-core

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/root-config - from package: libroot-core-dev

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

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