newvserver: 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/newvserver - from package: vserver-debiantools

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