hdp: 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/hdp - from package: hdf

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

On Debian possible default full paths are:

/usr/bin/hdp - from package: hdf4-tools

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

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