pack.php: 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/share/simplesamlphp/bin/pack.php - from package: simplesamlphp

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

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