mk_fol_names: 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/share/doc/mh-book/examples/mh/bin/mk_fol_names - from package: mh-book

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

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