hdf24to8: 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/hdf24to8 - from package: hdf

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

On Debian possible default full paths are:

/usr/bin/hdf24to8 - from package: hdf4-tools

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

Error in other languages:
hdf24to8: bevel nie gevind nie
hdf24to8: comandă negăsită
hdf24to8: comando não encontrado
hdf24to8: commande introuvable
hdf24to8: command not found
hdf24to8: käsku ei ole
hdf24to8: không tìm thấy lệnh
hdf24to8: komanda nerasta
hdf24to8: Kommando nicht gefunden.
hdf24to8: kommandot finns inte
hdf24to8: komut yok
hdf24to8: nie znaleziono polecenia
hdf24to8: níor aimsíodh an t-ordú
hdf24to8: no se encontró la orden
hdf24to8: no s'ha trobat l'ordre
hdf24to8: opdracht niet gevonden
hdf24to8: parancs nem található
hdf24to8: perintah tidak ditemukan
hdf24to8: príkaz nenájdený
hdf24to8: příkaz nenalezen
hdf24to8: команда не найдена
hdf24to8: командата не е открита
hdf24to8: 命令找不到
hdf24to8: コマンドが見つかりません