ncontext: 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/ncontext - from package: util-vserver

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

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