s3d_x11gate: 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/s3d_x11gate - from package: s3dx11gate

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

Error in other languages:
s3d_x11gate: bevel nie gevind nie
s3d_x11gate: comandă negăsită
s3d_x11gate: comando não encontrado
s3d_x11gate: commande introuvable
s3d_x11gate: command not found
s3d_x11gate: käsku ei ole
s3d_x11gate: không tìm thấy lệnh
s3d_x11gate: komanda nerasta
s3d_x11gate: Kommando nicht gefunden.
s3d_x11gate: kommandot finns inte
s3d_x11gate: komut yok
s3d_x11gate: nie znaleziono polecenia
s3d_x11gate: níor aimsíodh an t-ordú
s3d_x11gate: no se encontró la orden
s3d_x11gate: no s'ha trobat l'ordre
s3d_x11gate: opdracht niet gevonden
s3d_x11gate: parancs nem található
s3d_x11gate: perintah tidak ditemukan
s3d_x11gate: príkaz nenájdený
s3d_x11gate: příkaz nenalezen
s3d_x11gate: команда не найдена
s3d_x11gate: командата не е открита
s3d_x11gate: 命令找不到
s3d_x11gate: コマンドが見つかりません