cdfpsi: 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 Debian possible default full paths are:

/usr/bin/cdfpsi - from package: cdftools

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

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