gstm: 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/gstm - from package: gstm

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

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