2.11BSD#431 - /usr/man/cat3/getpwent.0

GETPWENT(3)	    UNIX Programmer's Manual	      GETPWENT(3)


NAME
     getpwent, getpwnam, getpwuid, setpassent, setpwfile,
     setpwent, endpwent - get password file entries

SYNOPSIS
     #include <sys/types.h>
     #include <pwd.h>

     struct passwd *getpwent()

     struct passwd *getpwnam(login)
     char *login;

     struct passwd *getpwuid(uid)
     uid_t uid;

     int setpassent(stayopen)
     int stayopen;

     void setpwfile(file)
     char *file;

     int setpwent()

     void endpwent()

DESCRIPTION
     Getpwent, getpwuid, and getpwnam each return a pointer to a
     structure containing the broken-out fields of a line in the
     password file.  This structure is defined by the include
     file <pwd.h>, and contains the following fields:

	  struct passwd {
	       char *pw_name;		/* user name */
	       char *pw_passwd;         /* encrypted password */
	       uid_t	 pw_uid;	/* user uid */
	       gid_t	 pw_gid;	/* user gid */
	       time_t	 pw_change;	/* password change time */
	       char *pw_class;		/* user access class */
	       char *pw_gecos;		/* Honeywell login info */
	       char *pw_dir;		/* home directory */
	       char *pw_shell;		/* default shell */
	       time_t	 pw_expire;	/* account expiration */
	  };

     These fields are more completely described in passwd(5).

     Getpwnam and getpwuid search the password database for a
     matching user name or user uid, respectively, returning the
     first one encountered.  Identical user names or user uids
     may result in undefined behavior.


Printed 11/26/99	February 23, 1989			1


GETPWENT(3)	    UNIX Programmer's Manual	      GETPWENT(3)


     Getpwent sequentially reads the password database and is
     intended for programs that wish to step through the complete
     list of users.

     All three routines will open the password file for reading,
     if necessary.

     Setpwfile changes the default password file to file, thus
     allowing the use of alternate password files.

     Setpassent opens the file or rewinds it if it is already
     open.  If stayopen is non-zero, file descriptors are left
     open, significantly speeding up subsequent calls.	This
     functionality is unnecessary for getpwent as it doesn't
     close its file descriptors by default.  It should also be
     noted that it is dangerous for long-running programs to use
     this functionality as the password file may be updated by
     chpass(1), passwd(1), or vipw(8).

     Setpwent is identical to setpassent with an argument of
     zero.

     Endpwent closes any open files.

     These routines have been written to ``shadow'' the password
     file, e.g.  allow only certain programs to have access to
     the encrypted password.  This is done by using the
     mkpasswd(8) program, which creates ndbm(3) databases that
     correspond to the password file, with the single exception
     that, rather than storing the encrypted password in the
     database, it stores the offset in the password file where
     the encrypted password may be found.  Getpwent, getpwnam,
     and getpwuid will use the ndbm files in preference to the
     ``real'' password files, only reading the password file
     itself, to obtain the encrypted password, if the process is
     running with an effective user id equivalent to super-user.
     If the password file itself is protected, and the ndbm files
     are not, this makes the password available only to programs
     running with super-user privileges.

FILES
     /etc/passwd

SEE ALSO
     getlogin(3), getgrent(3), ndbm(3), passwd(5)

DIAGNOSTICS
     The routines getpwent, getpwnam, and getpwuid, return a null
     pointer on EOF or error.  Setpassent and setpwent return 0
     on failure and 1 on success.  Endpwent and setpwfile have no
     return value.


Printed 11/26/99	February 23, 1989			2


GETPWENT(3)	    UNIX Programmer's Manual	      GETPWENT(3)


BUGS
     All information is contained in a static buffer which is
     overwritten by each new call.  It must be copied elsewhere
     to be retained.

     Intermixing calls to getpwent with calls to getpwnam or
     getpwuid, or intermixing calls to getpwnam and getpwuid,
     after using setpassent to require that file descriptors be
     left open, may result in undefined behavior.

     The routines getpwent, endpwent, setpassent, and setpwent
     are fairly useless in a networked environment and should be
     avoided, if possible.


Printed 11/26/99	February 23, 1989			3