[Linux] miscellaneous

Create directory tree in linux using C plusplus

https://www.tutorialspoint.com/how-can-i-create-directory-tree-using-cplusplus-in-linux

Example is not correct at all when it handle "status"

it should be:

#include <bits/stdc++.h>
#include <iostream>
#include <sys/stat.h>
#include <sys/types.h>
using namespace std;
int main() {
   int status;
   status = system("mkdir -p TP/My_Folder/test"); // Creating a directory
   if (status != 0)
      std::cerr << "Error : " << strerror(errno) << std::endl;
   else
      std::cout << "Directories are created" << std::endl;
}

What is default permission of command  "system("mkdir -p TP/My_Folder/test");"?
The answer is 755 or drwxr-xr-x

What is drwxr-xr-x?
It looks like 4 groups:  d  rwx  r-x  r-x
d: directory (file is "-")
rwx: owner can read/write/execute
r-x:  group user can read/execute
r-x:  other user can read/execute
Bonus: "-" is permission not set

What is "755"
ref: https://www.maketecheasier.com/file-permissions-what-does-chmod-777-means/

0 – no permission
1 – execute
2 – write
3 – write and execute
4 – read
5 – read and execute
6 – read and write
7 – read, write, and execute

Example: Try to create some directories and show default permission by command "ls"

Bonus ++: You may concern about command chmod options as below

Example:
1. Allow one file is run by user(owner)
chmod u+x runablefile.sh

2. Allow full permission with one file for group of user
chmod g+rwx groupfull.txt

The man page of chmod covers that.
u stands for user.
g stands for group.
o stands for others.
a stands for all.