hexbraille: 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/hexbraille - from package: unifont-bin

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

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