ifcfg: 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:

/sbin/ifcfg - from package: iproute

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

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