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getgrent.3

GETGRENT

Section: Linux Programmer's Manual (3)
Updated: 2009-03-30
Index Return to Main Contents
 

NAME

getgrent, setgrent, endgrent - get group file entry  

SYNOPSIS

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

struct group *getgrent(void);

void setgrent(void);

void endgrent(void);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

getgrent(), setgrent(), endgrent(): _SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE >= 500  

DESCRIPTION

The getgrent() function returns a pointer to a structure containing the broken-out fields of a record in the group database (e.g., the local group file /etc/group, NIS, and LDAP). The first time it is called it returns the first entry; thereafter, it returns successive entries.

The setgrent() function rewinds to the beginning of the group database, to allow repeated scans.

The endgrent() function is used to close the group database after all processing has been performed.

The group structure is defined in <grp.h> as follows:

struct group {
    char   *gr_name;       /* group name */
    char   *gr_passwd;     /* group password */
    gid_t   gr_gid;        /* group ID */
    char  **gr_mem;        /* group members */
};
 

RETURN VALUE

The getgrent() function returns a pointer to a group structure, or NULL if there are no more entries or an error occurs.

Upon error, errno may be set. If one wants to check errno after the call, it should be set to zero before the call.

The return value may point to a static area, and may be overwritten by subsequent calls to getgrent(), getgrgid(3), or getgrnam(3). (Do not pass the returned pointer to free(3).)  

ERRORS

EINTR
A signal was caught.
EIO
I/O error.
EMFILE
The calling process already has too many open files.
ENFILE
Too many open files in the system.
ENOMEM
Insufficient memory to allocate group structure.
ERANGE
Insufficient buffer space supplied.
 

FILES

/etc/group
local group database file
 

CONFORMING TO

SVr4, 4.3BSD, POSIX.1-2001.  

SEE ALSO

fgetgrent(3), getgrent_r(3), getgrgid(3), getgrnam(3), getgrouplist(3), putgrent(3)  

COLOPHON

This page is part of release 3.21 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
FILES
CONFORMING TO
SEE ALSO
COLOPHON

 

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