weston-launch: 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/weston-launch - from package: weston

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

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