vconfig: 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/vconfig - from package: vconfig

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

On Debian possible default full paths are:

/sbin/vconfig - from package: vlan

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

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