hdf8to24: 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/hdf8to24 - from package: hdf

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

On Debian possible default full paths are:

/usr/bin/hdf8to24 - from package: hdf4-tools

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

Error in other languages:
hdf8to24: bevel nie gevind nie
hdf8to24: comandă negăsită
hdf8to24: comando não encontrado
hdf8to24: commande introuvable
hdf8to24: command not found
hdf8to24: käsku ei ole
hdf8to24: không tìm thấy lệnh
hdf8to24: komanda nerasta
hdf8to24: Kommando nicht gefunden.
hdf8to24: kommandot finns inte
hdf8to24: komut yok
hdf8to24: nie znaleziono polecenia
hdf8to24: níor aimsíodh an t-ordú
hdf8to24: no se encontró la orden
hdf8to24: no s'ha trobat l'ordre
hdf8to24: opdracht niet gevonden
hdf8to24: parancs nem található
hdf8to24: perintah tidak ditemukan
hdf8to24: príkaz nenájdený
hdf8to24: příkaz nenalezen
hdf8to24: команда не найдена
hdf8to24: командата не е открита
hdf8to24: 命令找不到
hdf8to24: コマンドが見つかりません