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Manual page for GETGRENT(3V)

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 fields of a line in the group file. Each line contains a ``group'' structure, defined in <grp.h>.

struct	group {
	char	*gr_name;	/* name of the group */
	char	*gr_passwd;	/* encrypted password of the group */
	gid_t	gr_gid;		/* numerical group ID */
	char	**gr_mem;	/* null-terminated array of pointers to the
					individual 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. 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 must refer to an open file in the same format as the group file /etc/group.

RETURN VALUES

getgrent(), getgrgid(), and getgrnam() return a pointer to struct group on success. On EOF or error, they return NULL.

FILES

/etc/group

BUGS

All information is contained in a static area, so it must be copied if it is to be saved.

Unlike the corresponding routines for passwords (see getpwent.3v which always search the entire file, these routines start searching from the current file location.

WARNING

The above routines use the standard I/O library, which increases the size of programs not otherwise using standard I/O more than might be expected.