passwd encrypted in user file

Hello everybody, sorry for this question : i want to use encrypted passwd in "users" file without using unix files. So, i have to write : username Crypt-Password := "$1$5oVGRb3C$PCKT5Fv7d81NZTmzEm83e0". How does Freeradius link the encrypted password with password ? I want to run a command wich crypt password. Wich command could i use ? My system is unix-like. Then, i want to store this encrypted password in "users" file ? i look to man rlm_pap and i set yes to auto_header. Thanks for any answer.