shuffle: 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/shuffle - from package: biosquid

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

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