hdfimport: 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/hdfimport - from package: hdf

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

On Debian possible default full paths are:

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

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

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