scrypt: 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/scrypt - from package: scrypt

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

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