pylupdate4: 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:

/usr/bin/pylupdate4 - from package: PyQt4-devel

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

On Debian possible default full paths are:

/usr/bin/pylupdate4 - from package: pyqt4-dev-tools

You may install the required package with command apt-get install {package}
Error in other languages:
pylupdate4: bevel nie gevind nie
pylupdate4: comandă negăsită
pylupdate4: comando não encontrado
pylupdate4: commande introuvable
pylupdate4: command not found
pylupdate4: käsku ei ole
pylupdate4: không tìm thấy lệnh
pylupdate4: komanda nerasta
pylupdate4: Kommando nicht gefunden.
pylupdate4: kommandot finns inte
pylupdate4: komut yok
pylupdate4: nie znaleziono polecenia
pylupdate4: níor aimsíodh an t-ordú
pylupdate4: no se encontró la orden
pylupdate4: no s'ha trobat l'ordre
pylupdate4: opdracht niet gevonden
pylupdate4: parancs nem található
pylupdate4: perintah tidak ditemukan
pylupdate4: príkaz nenájdený
pylupdate4: příkaz nenalezen
pylupdate4: команда не найдена
pylupdate4: командата не е открита
pylupdate4: 命令找不到
pylupdate4: コマンドが見つかりません