drmm: 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/share/doc/mh-book/examples/mh/bin/drmm - from package: mh-book

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

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