passwd, chfn, chsh - change a login password, full name or shell
chfn [user] fullname
chfn [user] shell
passwd # Change current user's password
passwd ast # Change ast's password (super-user only)
chsh /usr/bin/mail # For those who only read mail
chfn 'Jane Doe' # Current user is Jane Doe
Passwd is used to change your password. It prompts for the old and new
passwords. It asks for the new password twice, to reduce the effect of a
typing error. Chfn changes the full name (GECOS field) in the password
file. Chsh changes your login shell. Do not forget to copy the modified
password file back to the root file system, or the changes will be lost
when the system is rebooted.
login(1), su(1), crypt(3), getpwent(3).