hersheydemo: 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/bin/hersheydemo - from package: plotutils

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

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