GETGRENT(3) MachTen Programmer’s Manual GETGRENT(3)

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

SYNOPSIS
#include <grp.h>

struct group *
getgrent(void)

struct group *
getgrnam(const char *name)

struct group *
getgrgid(gid_t gid)

struct group *
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 in-
tended 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, 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 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 oc-
curs a null pointer is returned. The functions setgroupent() and
setgrent() return the value 1 if successful, otherwise the value 0 is re-
turned. The functions endgrent() and setgrfile() have no return value.

FILES
/etc/group group database file