pyvenv-3.4: 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/pyvenv-3.4 - from package: python3.4-venv

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

Error in other languages:
pyvenv-3.4: bevel nie gevind nie
pyvenv-3.4: comandă negăsită
pyvenv-3.4: comando não encontrado
pyvenv-3.4: commande introuvable
pyvenv-3.4: command not found
pyvenv-3.4: käsku ei ole
pyvenv-3.4: không tìm thấy lệnh
pyvenv-3.4: komanda nerasta
pyvenv-3.4: Kommando nicht gefunden.
pyvenv-3.4: kommandot finns inte
pyvenv-3.4: komut yok
pyvenv-3.4: nie znaleziono polecenia
pyvenv-3.4: níor aimsíodh an t-ordú
pyvenv-3.4: no se encontró la orden
pyvenv-3.4: no s'ha trobat l'ordre
pyvenv-3.4: opdracht niet gevonden
pyvenv-3.4: parancs nem található
pyvenv-3.4: perintah tidak ditemukan
pyvenv-3.4: príkaz nenájdený
pyvenv-3.4: příkaz nenalezen
pyvenv-3.4: команда не найдена
pyvenv-3.4: командата не е открита
pyvenv-3.4: 命令找不到
pyvenv-3.4: コマンドが見つかりません