GETGRENT(3C) (C Programming Language Utilities) GETGRENT(3C)
NAME
getgrent, getgrgid, getgrnam, setgrent, endgrent, fgetgrent
- get group file entry
SYNOPSIS
#include <grp.h>
struct group *getgrent ( )
struct group *getgrgid (gid)
int gid;
struct group *getgrnam (name)
char *name;
void setgrent ( )
void endgrent ( )
struct group *fgetgrent (f)
FILE *f;
DESCRIPTION
getgrent, getgrgid and getgrnam each return pointers to an
object with the following structure containing the broken-
out fields of a line in the /etc/group file. Each line
contains a ``group'' structure, defined in the <grp.h>
header file.
struct group {
char *gr_name; /* the name of the group */
char *gr_passwd; /* the encrypted group password */
int gr_gid; /* the numerical group ID */
char **gr_mem; /* vector of pointers to 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 may be used to search the entire file.
Page 1 May 1989
GETGRENT(3C) (C Programming Language Utilities) GETGRENT(3C)
Getgrgid searches from the beginning of the file until a
numerical group id matching gid is found and returns a
pointer to the particular structure in which it was found.
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 end-
of-file or an error is encountered on reading, these
functions 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
SEE ALSO
getlogin(3C), getpwent(3C), group(4).
DIAGNOSTICS
A NULL pointer is returned on EOF or error.
WARNING
The above routines use <stdio.h>, which causes them to
increase the size of programs, not otherwise using standard
I/O, more than might be expected.
CAVEAT
All information is contained in a static area, so it must be
copied if it is to be saved.
Page 2 May 1989