vzifup-post: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

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/vzifup-post - from package: vzctl

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