funpack: 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/funpack - from package: libcfitsio-bin

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

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