GETGRENT

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

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <grp.h>

     struct group *
     getgrent(void);

     struct group *
     getgrnam(const char *name);

     struct group *
     getgrgid(gid_t gid);

     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 */
                   int     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.

     All three routines 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, significantly
     speeding functions subsequent calls.  This functionality is unnecessary
     for getgrent() 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 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
     the group entry if successful; if end-of-file is reached or an error
     occurs a null pointer is returned.  The functions setgroupent() and
     setgrent() return the value 1 if successful, otherwise the value 0 is
     returned.  The functions endgrent() and setgrfile() have no return value.

FILES
     /etc/group  group database file

SEE ALSO
     getpwent(3), yp(4), group(5)

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.

COMPATIBILITY
     The historic function setgrfile(), which allowed the specification of
     alternate password databases, has been deprecated and is no longer available.
     
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 modify
     the same object.

     The functions getgrent(), endgrent(), setgroupent(), and setgrent() are
     fairly useless in a networked environment and should be avoided, if possible.
     
BSD                           September 29, 1994                           BSD