Whant to write an entry in /etc/passwd (putpwent)

Applications Programming
1

Hi i try to use the function putpwent to write a simple
entry in "/etc/passwd" putpwnet returns 0 as it works but
notething writes to /etc/passwd. What have i missed?

My os
--------

root@nighter-laptop:/home/nighter/labb# uname -a
Linux nighter-laptop 2.6.22-14-generic #1 SMP Sun Oct 14 23:05:12 GMT 2007 i686 GNU/Linux

( Ubuntu )

My code
----

#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <pwd.h>
#include <grp.h>
#include <string.h>



int main()
{
   struct passwd p;
   long m=900;

   FILE *fd;
   memset(&p,0x00,sizeof(p));

   fd=fopen("/etc/passwd ","a");

        p.pw_name="kalle";
        p.pw_passwd="kalle";
        p.pw_uid=m;
        p.pw_gid=m;
        p.pw_gecos="Test account";
        p.pw_dir="/home/kalle";
        p.pw_shell="/bin/bash";

        int value = putpwent(&p,fd);

        printf("%i",value);


return 0;
}

------------------------

2

After opening /etc/passwd you need to seek to the end of the file i..e

fseek(fd, 0, SEEK_END);

You also need to close the file after writing the entry

fclose(fd);
3

I think there is no need of opening the passwd file with fopen when using functions from pwd.h

4

Actaully it was not that who where the problem!
But now it works! Don't understand why. But it do.

5

Hi i just whant to update an password entry in /etc/shadow.
But dosen't get it to work. Something is wrong! in this code.

What i try do do is if user kalle exist in shadow.
I whant it to update it's password for just that entry.

#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <pwd.h>
#include <grp.h>
#include <string.h>
#include <shadow.h>
//#include <userpw.h>

int main()
{
     // -------------------------- //
     // ------- passwd file ------ //
     // -------------------------- //
     FILE* fp;
     struct passwd *p;

     memset(&p, 0, sizeof(p));

     if (!(fp = fopen("/etc/passwd", "a"))) {
           perror("Problem ");
           return(1);
     }

     // --------------------------- //
     // ----- Password Crypt ------ //
     // --------------------------- //
     char salt[2];
     char password[8] = "password";
     char t[11];

     salt[0] = 'W'; salt[1] = 'M';
     strcpy(t,(char *)crypt(password, salt));

    // --------------------------- //
     // ------ shadow file -------- //
     // --------------------------- //

     FILE* fps;
     struct spwd *sp;
     memset(&sp, 0, sizeof(sp));
     if (!(fps = fopen("/etc/shadow", "rw"))) {
        perror("Problem");
        return(1);
     }

     char user[20] = "kalle";

     /* Loop thru passwd file */
     while ((p = getpwent()) != NULL) {
                printf("%s\n",p->pw_name);

                //IF user found 
                if (strcmp(p->pw_name, user) == 0 ) {

                        if(!(sp=getspnam(p->pw_name))){
                                printf("user missing in shadow file");
                        } else {
                                strcpy(sp->sp_pwdp,t);
                                prinf("run the train %s\n",sp->sp_pwdp);
                                putspent(sp,fps);
                        }

                    
                }

    }

       
    fclose(fps);
  
 return( EXIT_SUCCESS );
}
6

wrong button it was intended to be a new threat.