unique-messages.py: 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 CentOS possible default full paths are:

/usr/lib/python2.6/site-packages/django/bin/unique-messages.py - from package: Django14

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

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