repo-graph: 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/repo-graph - from package: yum-utils

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

On Debian possible default full paths are:

/usr/bin/repo-graph - from package: yum-utils

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

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