gst-config: 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/gst-config - from package: libgst-dev

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

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