redcarpet: 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/redcarpet - from package: rubygem-redcarpet
/usr/lib/ruby/gems/1.8/gems/redcarpet-2.1.1/bin/redcarpet - from package: rubygem-redcarpet

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

On Debian possible default full paths are:

/usr/bin/redcarpet - from package: ruby-redcarpet

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

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