tdpackdemo: 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/tdpackdemo - from package: ncl

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

On Debian possible default full paths are:

/usr/bin/tdpackdemo - from package: ncl-ncarg

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

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