hdfls: 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/hdfls - from package: hdf

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

On Debian possible default full paths are:

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

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

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