post_faq: 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/post_faq - from package: post-faq

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

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