UNIX (not Linux) password change with C

Question

I already know that I can read the password structure (getpwnam etc.) but how can I alter the specific password. Do I have to lock the master.passwd and modify it directly or better make a copy from master.passwd modify this and make a file move after correct modifications?

At last, I don't want to make a system(usermod ...) because that invokes the shell and should be the last solution!

Thanks in advance

Thanks for the hints! My solution is now very close to the solution in OpenBSD's local_passwd.c Which uses the functions pw_lock(), pw_init() and pw_mkdb(). These functions let you also do some modifications if you're using the old passwd or the spwd.db. — user1194264
– user1194264, Commented Feb 8, 2012 at 12:47

Coren · Accepted Answer · 2012-02-07 09:58:04Z

2

In C for Unix like Solaris or AIX , you can either :

Use PAM API if available. Here are some articles about it on Solaris.
Add a new password with putpwent
Change existing password with getpwent, crypt your new password and finish with endpwent

You'll see here a complete sample program to change a pasword for unix in C using putpwent & getpwent. AIX documentation seems to confirm it should also works on their OS.

answered Feb 7, 2012 at 9:58

Coren

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1 Comment

R.. GitHub STOP HELPING ICE Over a year ago

If the passwords are stored in the passwd file and not shadow or equivalent, why even bother setting a password? All it does is make it so it takes 3 hours longer to login as whoever you want... ;-)

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