gm-install_arriba: command not found

Have You tried accessing the binary with the full path?

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/sbin/gm-install_arriba - from package: gnumed-client-de

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