getgrgid()--Get Group Information Using Group ID

 #include <grp.h>

 struct group *getgrgid(gid_t gid);  

The getgrgid() function returns a pointer to an object of type struct group containing an entry from the user database with a matching GID.

Parameters

gid

(Input) Group ID.

Authorities

*READ authority is required to the user profile associated with the gid. If the user does not have *READ authority, only the name of the group and the group ID values are returned.

Return Value

struct group *

getgrgid() was successful. The return value points to static data of the format struct group, which is defined in the grp.h header file. This storage is overwritten on each call to this function. This static storage area is also used by the getgrnam() function. The struct group has the following elements:

char *	gr_name	Name of the group
gid_t	gr_gid	Group ID
char **	gr_mem	A null-terminated list of pointers to the individual member profile names. If the group profile does not have any members or if the caller does not have *READ authority to the group profile, the list will be empty.

NULL pointer

getgrgid was not successful. The errno global variable is set to indicate the error.

Error Conditions

If getgrgid() is not successful, errno usually indicates one of the following errors. Under some conditions, errno could indicate an error other than those listed here.

Related Information

• The <grp.h> file (see Header Files for UNIX-Type Functions)
  
• getgrgid_r()--Get Group Information Using Group ID

Example

See Code disclaimer information for information pertaining to code examples.

The following example gets the group information for the gid of 91. The group name is GROUP1. There are two group members, CLIFF and PATRICK.

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

main()
{
  struct group *grp;
  short int    lp;

  if (NULL == (grp = getgrgid(91)))
     perror("getgrgid() error.");
  else
  {
     printf("The group name is: %s\n", grp->gr_name);
     printf("The gid        is: %u\n", grp->gr_gid);
     for (lp = 1; NULL != *(grp->gr_mem); lp++, (grp->gr_mem)++)
        printf("Group member %d is: %s\n", lp, *(grp->gr_mem));
  }

}

Output:

  The group name is: GROUP1
  The gid        is: 91
  Group member 1 is: CLIFF
  Group member 2 is: PATRICK