pypy: 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/pypy - from package: pypy

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

On Debian possible default full paths are:

/usr/bin/pypy - from package: pypy

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

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