mkfastmod: 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/mkfastmod - from package: sword

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

On Debian possible default full paths are:

/usr/bin/mkfastmod - from package: libsword-utils

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

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