文件权限umask mode chmod

一、umask

linux命令–umask

二、 chmod

int chmod(const char *path, mode_t mode);
chmod第二个参数既可以用以下宏位或的方式，也可以直接传一个8进制数，效果一样

The new file permissions are specified in mode, which is a bit mask created by ORing together zero or more of the following:
	S_ISUID  (04000)  set-user-ID (set process effective user ID on execve(2))
	S_ISGID  (02000)  set-group-ID (set process effective group ID on execve(2); mandatory  lock‐
					 ing,  as  described in fcntl(2); take a new file's group from parent direc‐
					 tory, as described in chown(2) and mkdir(2))
	S_ISVTX  (01000)  sticky bit (restricted deletion flag, as described in unlink(2))
	S_IRUSR  (00400)  read by owner
	S_IWUSR  (00200)  write by owner
	S_IXUSR  (00100)  execute/search by owner ("search" applies for directories, and  means  that
					 entries within the directory can be accessed)
	S_IRGRP  (00040)  read by group
	S_IWGRP  (00020)  write by group
	S_IXGRP  (00010)  execute/search by group
	S_IROTH  (00004)  read by others
	S_IWOTH  (00002)  write by others
	S_IXOTH  (00001)  execute/search by others 


root@lipenghui-virtual-machine:/mnt/hgfs/vmshare/process# ls -al /tmp/1123 
-rw-r--r-- 1 root root 0  4月 26 09:42 /tmp/1123

root@lipenghui-virtual-machine:/mnt/hgfs/vmshare/process# ls -al /tmp/1124
-rw-r--r-- 1 root root 0  4月 26 09:42 /tmp/1124

chmod("/tmp/1123", 0777);
chmod("/tmp/1124", S_IRUSR | S_IWUSR | S_IXUSR | S_IRGRP | S_IWGRP | S_IXGRP | S_IROTH | S_IWOTH | S_IXOTH);
	
	
root@lipenghui-virtual-machine:/mnt/hgfs/vmshare/process# ls -al /tmp/1124
-rwxrwxrwx 1 root root 0  4月 26 09:42 /tmp/1124
root@lipenghui-virtual-machine:/mnt/hgfs/vmshare/process# ls -al /tmp/1123
-rwxrwxrwx 1 root root 0  4月 26 09:42 /tmp/1123