hmackeys: command not found

Have You tried accessing the binary with the full path?

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/hmackeys - from package: ion

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