vzcalc: 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
/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/vzcalc - from package: vzctl

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