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GETGRENT(3)	       FreeBSD Library Functions Manual		   GETGRENT(3)

NAME
     getgrent, getgrent_r, getgrnam, getgrnam_r, getgrgid, getgrgid_r,
     setgroupent, setgrent, endgrent --	group database operations

LIBRARY
     Standard C	Library	(libc, -lc)

SYNOPSIS
     #include <grp.h>

     struct group *
     getgrent(void);

     int
     getgrent_r(struct group *grp, char	*buffer, size_t	bufsize,
	 struct	group **result);

     struct group *
     getgrnam(const char *name);

     int
     getgrnam_r(const char *name, struct group *grp, char *buffer,
	 size_t	bufsize, struct	group **result);

     struct group *
     getgrgid(gid_t gid);

     int
     getgrgid_r(gid_t gid, struct group	*grp, char *buffer, size_t bufsize,
	 struct	group **result);

     int
     setgroupent(int stayopen);

     int
     setgrent(void);

     void
     endgrent(void);

DESCRIPTION
     These functions operate on	the group database file	/etc/group which is
     described in group(5).  Each line of the database is defined by the
     structure group found in the include file <grp.h>:

	   struct group	{
		   char	   *gr_name;	   /* group name */
		   char	   *gr_passwd;	   /* group password */
		   gid_t   gr_gid;	   /* group id */
		   char	   **gr_mem;	   /* group members */
	   };

     The functions getgrnam() and getgrgid() search the	group database for the
     given group name pointed to by name or the	group id pointed to by gid,
     respectively, returning the first one encountered.	 Identical group names
     or	group gids may result in undefined behavior.

     The getgrent() function sequentially reads	the group database and is
     intended for programs that	wish to	step through the complete list of
     groups.

     The functions getgrent_r(), getgrnam_r(), and getgrgid_r()	are thread-
     safe versions of getgrent(), getgrnam(), and getgrgid(), respectively.
     The caller	must provide storage for the results of	the search in the grp,
     buffer, bufsize, and result arguments.  When these	functions are success-
     ful, the grp argument will	be filled-in, and a pointer to that argument
     will be stored in result.	If an entry is not found or an error occurs,
     result will be set	to NULL.

     These functions will open the group file for reading, if necessary.

     The setgroupent() function	opens the file,	or rewinds it if it is already
     open.  If stayopen	is non-zero, file descriptors are left open, signifi-
     cantly speeding functions subsequent calls.  This functionality is	unnec-
     essary for	getgrent() as it does not 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 group file may be updated.

     The setgrent() function is	identical to setgroupent() with	an argument of
     zero.

     The endgrent() function closes any	open files.

RETURN VALUES
     The functions getgrent(), getgrnam(), and getgrgid(), return a pointer to
     a group structure on success or NULL if the entry is not found or if an
     error occurs.  If an error	does occur, errno will be set.	Note that pro-
     grams must	explicitly set errno to	zero before calling any	of these func-
     tions if they need	to distinguish between a non-existent entry and	an
     error.  The functions getgrent_r(), getgrnam_r(), and getgrgid_r()	return
     0 if no error occurred, or	an error number	to indicate failure.  It is
     not an error if a matching	entry is not found.  (Thus, if result is set
     to	NULL and the return value is 0,	no matching entry exists.)

     The functions setgroupent() and setgrent()	return the value 1 if success-
     ful, otherwise the	value 0	is returned.  The functions endgrent() and
     setgrfile() have no return	value.

FILES
     /etc/group	 group database	file

COMPATIBILITY
     The historic function setgrfile(),	which allowed the specification	of
     alternate password	databases, has been deprecated and is no longer	avail-
     able.

SEE ALSO
     getpwent(3), group(5), nsswitch.conf(5), yp(8)

STANDARDS
     The getgrent(), getgrnam(), getgrnam_r(), getgrgid(), getgrgid_r()	and
     endgrent()	functions conform to ISO/IEC 9945-1:1996 (``POSIX.1'').	 The
     setgrent()	function differs from that standard in that its	return type is
     int rather	than void.

HISTORY
     The functions endgrent(), getgrent(), getgrnam(), getgrgid(), and
     setgrent()	appeared in Version 7 AT&T UNIX.  The functions	setgrfile()
     and setgroupent() appeared	in 4.3BSD-Reno.	 The functions getgrent_r(),
     getgrnam_r(), and getgrgid_r() appeared in	FreeBSD	5.1.

BUGS
     The functions getgrent(), getgrnam(), getgrgid(), setgroupent() and
     setgrent()	leave their results in an internal static object and return a
     pointer to	that object.  Subsequent calls to the same function will mod-
     ify the same object.

     The functions getgrent(), getgrent_r(), endgrent(), setgroupent(),	and
     setgrent()	are fairly useless in a	networked environment and should be
     avoided, if possible.  The	getgrent() and getgrent_r() functions make no
     attempt to	suppress duplicate information if multiple sources are speci-
     fied in nsswitch.conf(5).

FreeBSD	9.2			April 16, 2003			   FreeBSD 9.2

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | FILES | COMPATIBILITY | SEE ALSO | STANDARDS | HISTORY | BUGS

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