cython: 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/cython - from package: Cython

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

On Debian possible default full paths are:

/usr/bin/cython - from package: Cython

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

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