Index for Section 3

Alphabetical listing for G

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getgrent(3)
NAME
  endgrent, fgetgrent, getgrent, getgrgid, getgrnam, setgrent, endgrent_r,
  fgetgrent_r, getgrent_r, getgrgid_r, getgrnam_r, setgrent_r - Access group
  information in the user database

LIBRARY
  Standard C Library (libc)

SYNOPSIS
  #include <grp.h>

  void endgrent(void);

  struct group *fgetgrent(
	  FILE *f);

  struct group *getgrent(void);

  struct group *getgrgid(
	  gid_t gid);

  struct group *getgrnam(
	  const char *name);

  void setgrent(void);

  void endgrent_r(
	  FILE **gr_fp);

  int fgetgrent_r(
	  FILE *f,
	  struct group *grp,
	  char *buffer,
	  int len);

  int getgrent_r(
	  struct group *grp,
	  char *buffer,
	  int len,
	  FILE **gr_fp);

  int getgrgid_r(
	  gid_t gid,
	  struct group *grp,
	  char *buffer,
	  size_t len,
	  struct group **result);

  int getgrnam_r(
	  const char *name,
	  struct group *grp,
	  char *buffer,
	  size_t len,
	  struct group **result);


  int setgrent_r(
	  FILE **gr_fp);

  The following obsolete functions do not conform to industry standards and
  are supported only for backward compatibility.  You should not use them in
  new designs.


  int getgrgid_r(
	  gid_t gid,
	  struct group *grp,
	  char *buffer,
	  int len);

  int getgrnam_r(
	  const char *name,
	  struct group *grp,
	  char *buffer,
	  int len);

  int setgrent(void);

STANDARDS
  Interfaces documented on this reference page conform to industry standards
  as follows:

  endgrent, getgrent, getgrgid, getgrgid_r, getgrnam, getgrnam_r, setgrent:
  XSH5.0

  Refer to the standards(5) reference page for more information about
  industry standards and associated tags.

PARAMETERS
  name	    Specifies the name of the group for which the group file entry is
	    to be retrieved.

  gid	    Specifies the group ID of the group for which the group file
	    entry is to be retrieved.

  grp	    Provides storage to hold the retrieved group structure.

  buffer    Specifies the working buffer that is able to hold the longest
	    group entry in the database (/etc/group).

  len	    Specifies the length of buffer.  This length should be sufficient
	    for buf to hold the longest /etc/group line.

  result    Upon successful return, points to the retrieved group structure.
	    Upon unsuccessful return, the result is set to NULL.

  gr_fp	    Specifies a file that contains the next group structure
	    (initialized by the user).

  f	    Specifies a file that contains the next group structure
	    (initialized by the user). This file should have the same format
	    as /etc/group.  The minimum buffer size is 1024 bytes as defined
	    for SIABUFSIZ in /usr/include/sia.h.

  len	    Specifies the length of buffer.  The minimum buffer size is 1024
	    bytes as defined for SIABUFSIZ in /usr/include/sia.h.




DESCRIPTION
  The getgrent, getgrgid, getgrnam, setgrent, endgrent, and fgetgrent
  functions may be used to access the basic group attributes.

  The setgrent function opens the user database (if not already open) and
  rewinds to the first group entry in the database.

  The getgrent, getgrnam, and getgrgid functions return information about the
  requested group. The getgrent function returns the next group in the
  sequential search.  The getgrnam function returns the first group in the
  database with the gr_name field that matches the name parameter.  The
  getgrgid function returns the first group in the database with a gr_gid
  field that matches the gid parameter.	 The endgrent function closes the
  user database.

  The group structure, which is returned by the getgrent, getgrgid, and
  getgrnam functions, is defined in the grp.h header file, and contains the
  following members:

  gr_name   The name of the group.

  gr_passwd The password of the group.	(Note that this field is not used by
	    the system, so its value is meaningless.)

  gr_gid    The ID of the group.

  gr_mem    The members of the group.

  The fgetgrent function gets a group file entry from the file specified by
  the f parameter, rather than assuming that it comes from the /etc/group
  file.	 This file must have the format of the /etc/group file.

  The endgrent_r, fgetgrent_r, getgrent_r, getgrgid_r, getgrnam_r, and
  setgrent_r, functions are the reentrant versions of endgrent, fgetgrent,
  getgrent, getgrgid, getgrnam, and setgrent, respectively.

  The endgrent_r, fgetgrent_r, getgrent_r, and setgrent_r, functions use the
  f and gr_fp parameters to keep track of the calls to the getgrent_r
  function, so that subsequent calls will return subsequent entries from the
  /etc/group file.

  Upon successful completion, the fgetgrent_r, getgrent_r, getgrgid_r, and
  getgrnam_r functions store their results in the buffer pointed to by the
  grp parameter, with references to the working buffer.	 The pointer to the
  grp is also stored in result.

NOTES
  The data that is returned by the fgetgrent, getgrent, getgrgid, and
  getgrnam functions is stored in a static area and will be overwritten on
  subsequent calls to these routines.

  The fgetgrent, getgrent, getgrnam, and getgrgid functions are not supported
  for multithreaded applications.  Instead, their reentrant equivalents,
  fgetgrent_r, getgrent_r, getgrnam_r, and getgrgid_r, should be used with
  multiple threads.

  Note that the caller is expected to initialize *gr_fp to NULL before using
  it for the first time.

  Note also that entries which are excessively long will be ignored by both
  the reentrant and non-reentrant functions.



RETURN VALUES
  Upon successful completion, the fgetgrent, getgrent, getgrgid, and getgrnam
  functions return a pointer to a valid group structure containing a matching
  entry. Upon failure, these functions return NULL.

  The getgrgid_r and getgrnam_r functions return a value of 0 (zero) on
  success and an error number on failure.

  The fgetgrent_r and getgrent_r functions, as well as the obsolete versions
  of the getgrgid_r and getgrnam_r functions, return a value of 0 (zero) for
  success and a value of -1 for failure.

  The backward-compatible version of the setgrent function returns a value of
  1 for success and a value of 0 (zero) for failure.

  The setgrent_r function returns a value of 0 (zero) for success and a value
  of -1 for failure.

ERRORS
  If any of the following conditions occurs, the getgrgid_r and getgrnam_r
  functions set errno to the corresponding value:

  [ERANGE]  The amount of storage specified by buffer and len is too small to
	    contain the data to be referenced by the resulting struct group
	    structure.

RELATED INFORMATION
  Functions: getpwent(3)

  Standards: standards(5)

Index for Section 3

Alphabetical listing for G

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