每天整理点Linux--umask | chmod

#include "apue.h"
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <stdlib.h>

#define RWRWRW (S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH)

int main()
{
    struct stat statbuf;
    //更改进程的 umask值不会改变 其父进程的umask
    umask(0);
    if (creat("foo", RWRWRW) < 0)
    {
        printf("create error");
        exit(0);
    }
    umask(S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH);
    if (creat("bar", RWRWRW) < 0)
    {
        printf("create error");
        exit(0);
    }
    
    /* chmod 改变文件访问权限  */
    
    /*
    if (stat("foo", &statbuf) <0 )
    {
        printf("stat error");
        exit(0);
    }
    // S_IXGRP 执行时设置组ID  设置了组ID位 关闭了组执行位
    if (chmod("foo", (statbuf.st_mode & ~S_IXGRP) | S_ISGID ) < 0 )
    {
        printf("chmod foo error");
        exit(0);
    }
    if (chmod("bar", S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH))
    {
        printf("chmod bar error");
        exit(0);
    }
    */
    return 0;
}