kramdown: 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 Debian possible default full paths are:

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

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

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