gadmin-openvpn-client: 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/lib/debug/usr/sbin/gadmin-openvpn-client - from package: gadmin-openvpn-client-dbg
/usr/sbin/gadmin-openvpn-client - from package: gadmin-openvpn-client

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

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