hdf2jpeg: 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/hdf2jpeg - from package: hdf

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

On Debian possible default full paths are:

/usr/bin/hdf2jpeg - from package: hdf4-tools

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

Error in other languages:
hdf2jpeg: bevel nie gevind nie
hdf2jpeg: comandă negăsită
hdf2jpeg: comando não encontrado
hdf2jpeg: commande introuvable
hdf2jpeg: command not found
hdf2jpeg: käsku ei ole
hdf2jpeg: không tìm thấy lệnh
hdf2jpeg: komanda nerasta
hdf2jpeg: Kommando nicht gefunden.
hdf2jpeg: kommandot finns inte
hdf2jpeg: komut yok
hdf2jpeg: nie znaleziono polecenia
hdf2jpeg: níor aimsíodh an t-ordú
hdf2jpeg: no se encontró la orden
hdf2jpeg: no s'ha trobat l'ordre
hdf2jpeg: opdracht niet gevonden
hdf2jpeg: parancs nem található
hdf2jpeg: perintah tidak ditemukan
hdf2jpeg: príkaz nenájdený
hdf2jpeg: příkaz nenalezen
hdf2jpeg: команда не найдена
hdf2jpeg: командата не е открита
hdf2jpeg: 命令找不到
hdf2jpeg: コマンドが見つかりません