unit2.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/bin/unit2.py - from package: python-unittest2

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

Error in other languages:
unit2.py: bevel nie gevind nie
unit2.py: comandă negăsită
unit2.py: comando não encontrado
unit2.py: commande introuvable
unit2.py: command not found
unit2.py: käsku ei ole
unit2.py: không tìm thấy lệnh
unit2.py: komanda nerasta
unit2.py: Kommando nicht gefunden.
unit2.py: kommandot finns inte
unit2.py: komut yok
unit2.py: nie znaleziono polecenia
unit2.py: níor aimsíodh an t-ordú
unit2.py: no se encontró la orden
unit2.py: no s'ha trobat l'ordre
unit2.py: opdracht niet gevonden
unit2.py: parancs nem található
unit2.py: perintah tidak ditemukan
unit2.py: príkaz nenájdený
unit2.py: příkaz nenalezen
unit2.py: команда не найдена
unit2.py: командата не е открита
unit2.py: 命令找不到
unit2.py: コマンドが見つかりません