getgrent(3) - NetBSD Manual Pages

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GETGRENT(3)               NetBSD Programmer's Manual               GETGRENT(3)


NAME

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


LIBRARY

     Standard C Library (libc, -lc)


SYNOPSIS

     #include <sys/types.h>
     #include <grp.h>

     struct group *
     getgrent(void);

     struct group *
     getgrnam(const char *name);

     struct group *
     getgrgid(gid_t gid);

     int
     setgroupent(int stayopen);

     void
     setgrent(void);

     void
     endgrent(void);


DESCRIPTION

     These functions operate on the group database file 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 in-
     tended for programs that wish to step through the complete list of
     groups.

     All three 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 doesn't close its file descriptors by de-
     fault.  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 equivalent 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 oc-
     curs a null pointer is returned.  The setgroupent() function returns the
     value 1 if successful, otherwise the value 0 is returned.  The endgrent()
     and setgrent() functions have no return value.


FILES

     /etc/group  group database file


SEE ALSO

     getpwent(3), group(5), nsswitch.conf(5)


STANDARDS

     The getgrnam() and getgrgid() functions conform to IEEE Std1003.1-1990
     (``POSIX'').


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 al-
     ternative password databases, has been deprecated and is no longer avail-
     able.


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 pos-
     sible.  getgrent() makes no attempt to suppress duplicate information if
     multiple sources are specified in nsswitch.conf(5)

NetBSD 1.4                      April 25, 1999                               2