gm-download_data: 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/gnumed/bin/gm-download_data - from package: gnumed-client

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

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