cdfflxconv: command not found

Have You tried accessing the binary with the full path?

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 Debian possible default full paths are:

/usr/bin/cdfflxconv - from package: cdftools

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