vcontext: 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 Debian possible default full paths are:

/usr/sbin/vcontext - from package: util-vserver

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

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