markdown2: 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/markdown2 - from package: python-markdown2

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

Error in other languages:
markdown2: bevel nie gevind nie
markdown2: comandă negăsită
markdown2: comando não encontrado
markdown2: commande introuvable
markdown2: command not found
markdown2: käsku ei ole
markdown2: không tìm thấy lệnh
markdown2: komanda nerasta
markdown2: Kommando nicht gefunden.
markdown2: kommandot finns inte
markdown2: komut yok
markdown2: nie znaleziono polecenia
markdown2: níor aimsíodh an t-ordú
markdown2: no se encontró la orden
markdown2: no s'ha trobat l'ordre
markdown2: opdracht niet gevonden
markdown2: parancs nem található
markdown2: perintah tidak ditemukan
markdown2: príkaz nenájdený
markdown2: příkaz nenalezen
markdown2: команда не найдена
markdown2: командата не е открита
markdown2: 命令找不到
markdown2: コマンドが見つかりません