ifnames268: 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/ifnames268 - from package: autoconf268

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

Error in other languages:
ifnames268: bevel nie gevind nie
ifnames268: comandă negăsită
ifnames268: comando não encontrado
ifnames268: commande introuvable
ifnames268: command not found
ifnames268: käsku ei ole
ifnames268: không tìm thấy lệnh
ifnames268: komanda nerasta
ifnames268: Kommando nicht gefunden.
ifnames268: kommandot finns inte
ifnames268: komut yok
ifnames268: nie znaleziono polecenia
ifnames268: níor aimsíodh an t-ordú
ifnames268: no se encontró la orden
ifnames268: no s'ha trobat l'ordre
ifnames268: opdracht niet gevonden
ifnames268: parancs nem található
ifnames268: perintah tidak ditemukan
ifnames268: príkaz nenájdený
ifnames268: příkaz nenalezen
ifnames268: команда не найдена
ifnames268: командата не е открита
ifnames268: 命令找不到
ifnames268: コマンドが見つかりません