ghb: 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/ghb - from package: handbrake

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

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