multimarkdown: 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/multimarkdown - from package: libtext-multimarkdown-perl

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

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