C Programming Code Examples
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Program to get the GroupID ( GID ) information
/* Program to get the GroupID ( GID ) information */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
int main()
{
gid_t gid;
if ((gid = getgid()) < 0) {
perror("
getgid error");
} else {
printf("
The group id is : %d", gid);
}
if ((gid = getegid()) < 0) {
perror("
getegid error");
} else {
printf("
The effective group id is : %d", gid);
}
printf("
");
return(0);
}
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getgid() returns the real group ID of the calling process. getegid() returns the effective group ID of the calling process. The getegid() function shall always be successful and no return value is reserved to indicate an error. The original Linux getgid() and getegid() system calls supported only 16-bit group IDs. Subsequently, Linux 2.4 added getgid32() and getegid32(), supporting 32-bit IDs. The glibc getgid() and getegid() wrapper functions transparently deal with the variations across kernel versions. On Alpha, instead of a pair of getgid() and getegid() system calls, a single getxgid() system call is provided, which returns a pair of real and effective GIDs. The glibc getgid() and getegid() wrapper functions transparently deal with this.
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