estmaster: 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/estmaster - from package: hyperestraier

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

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