pip2: 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/pip2 - from package: python-pip

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

On Debian possible default full paths are:

/usr/bin/pip2 - from package: python-pip

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

Error in other languages:
pip2: bevel nie gevind nie
pip2: comandă negăsită
pip2: comando não encontrado
pip2: commande introuvable
pip2: command not found
pip2: käsku ei ole
pip2: không tìm thấy lệnh
pip2: komanda nerasta
pip2: Kommando nicht gefunden.
pip2: kommandot finns inte
pip2: komut yok
pip2: nie znaleziono polecenia
pip2: níor aimsíodh an t-ordú
pip2: no se encontró la orden
pip2: no s'ha trobat l'ordre
pip2: opdracht niet gevonden
pip2: parancs nem található
pip2: perintah tidak ditemukan
pip2: príkaz nenájdený
pip2: příkaz nenalezen
pip2: команда не найдена
pip2: командата не е открита
pip2: 命令找不到
pip2: コマンドが見つかりません