gm-upgrade_server: 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/sbin/gm-upgrade_server - from package: gnumed-server

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

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