dreg: 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/dreg - from package: emboss

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

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