pserve3: 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/pserve3 - from package: python3-pyramid

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

Error in other languages:
pserve3: bevel nie gevind nie
pserve3: comandă negăsită
pserve3: comando não encontrado
pserve3: commande introuvable
pserve3: command not found
pserve3: käsku ei ole
pserve3: không tìm thấy lệnh
pserve3: komanda nerasta
pserve3: Kommando nicht gefunden.
pserve3: kommandot finns inte
pserve3: komut yok
pserve3: nie znaleziono polecenia
pserve3: níor aimsíodh an t-ordú
pserve3: no se encontró la orden
pserve3: no s'ha trobat l'ordre
pserve3: opdracht niet gevonden
pserve3: parancs nem található
pserve3: perintah tidak ditemukan
pserve3: príkaz nenájdený
pserve3: příkaz nenalezen
pserve3: команда не найдена
pserve3: командата не е открита
pserve3: 命令找不到
pserve3: コマンドが見つかりません