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

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

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

     struct group *
     getgrent(void);

     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);

     void
     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 struct 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.

     getgrent() sequentially reads the group database and is intended for pro-
     grams that wish to step through the complete list of groups.

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

     setgroupent() opens the file, or rewinds it if it is already open.  If
     stayopen is non-zero, file descriptors are left open, significantly
     speeding subsequent function 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.

     setgrent() is equivalent to setgroupent() with an argument of zero.

     The endgrent() function closes any open files.

     The getgrgid_r() and getgrnam_r() functions both update the group struc-
     ture pointed to by grp and store a pointer to that structure at the loca-
     tion pointed to by result.  The structure is filled with an entry from
     the group database with a matching gid or name.  Storage referenced by
     the group structure will be allocated from the memory provided with the
     buffer parameter, which is bufsiz characters in size.

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 0.  The endgrent() and setgrent() func-
     tions have no return value.  The functions getgrgid_r() and getgrnam_r()
     store a null pointer at the location pointed to by result and return the
     error number if an error occurs, or the requested entry is not found.

FILES
     /etc/group  group database file

SEE ALSO
     getpwent(3), 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.

     The historic function setgrfile(3), which allowed the specification of
     alternate 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 modi-
     fy the same object.

     The functions getgrent(), endgrent(), setgroupent(), and setgrent() are
     fairly useless in a networked environment and should be avoided, if pos-
     sible.

OpenBSD 3.4                     April 19, 1994                               2

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUES | FILES | SEE ALSO | HISTORY | BUGS

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