GETGRENT

Section: MINTLIB LIBRARY FUNCTIONS (3)
Updated: 3 March 1993
Index Return to Main Contents

NAME

getgrent, getgrgid, getgrnam, setgrent, endgrent, fgetgrent - get group file entry

SYNOPSIS

#include <stdio.h>
#include <grp.h>

struct group *getgrent(void);

struct group *getgrgid(int gid);

struct group *getgrnam(const char *name);

void setgrent(void);

void endgrent(void);

struct group *fgetgrent(FILE *f);

DESCRIPTION

getgrent, getgrgid and getgrnam each returns a pointer to an object containing the broken-out fields of a line in the /etc/group file. Each line in the file contains a "group" structure, declared in the <grp.h> header file:

  struct group
  {
    char  *gr_name;   /* name of the group     */
    char  *gr_passwd; /* encrypted password    */
    gid_t gr_gid;     /* numerical group ID    */
    char  **gr_mem;   /* array of member names */
  }; getgrent when first called returns a pointer to the first group structure in the file; thereafter, it returns a pointer to the next group structure in the file; so successive calls can be used to search the entire file. getgrgid searches from the beginning of the file until a numerical group ID is found matching gid is found and returns a pointer to the particular structure in which it was found. Thus, it cannot be found to search for several groups having duplicate numerical group IDs. getgrnam searches from the beginning of the file until a group name matching name is found and returns a pointer to the particular structure in which it was found. If an EOF or an error is encountered on reading, getgrent, getgrgid and getgrnam return a NULL pointer. A call to setgrent has the effect of rewinding the group file to allow repeated searches. endgrent may be called to close the group file when processing is complete. fgetgrent returns a pointer to the next group structure in the stream f, which matches the format of /etc/group.

FILES

/etc/group

NOTES

All information is contained in a static area, so it must be copied if it is to be saved. These routines cannot handle groups with over 128 members. These routines expect the group file to be of type text, and can therefore read both DOS and UN*X format files. fgetgrent is not standard, but is available on System V. For group files, there's no equivalent to putpwent. The password field of groups is seldom used.

This document was created by man2html, using the manual pages.
Time: 11:14:57 GMT, June 22, 2025