ncks: 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 CentOS possible default full paths are:

/usr/bin/ncks - from package: nco

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/ncks - from package: nco

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

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