vstp: command not found

Have You tried accessing the binary with the full path?

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 CentOS possible default full paths are:

/bin/vstp - from package: brlapi

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/vstp - from package: brltty

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