yum-config-manager: 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/yum-config-manager - from package: yum-utils

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

On Debian possible default full paths are:

/usr/bin/yum-config-manager - from package: yum-utils

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

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