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std::filesy...perm_options(3)  C++ Standard Libary std::filesy...perm_options(3)

NAME
     std::filesystem::perm_options - std::filesystem::perm_options

Synopsis
	Defined in header <filesystem>
	enum class perm_options {

	    replace = /* unspecified */,
	    add = /* unspecified */,	  (since C++17)
	    remove = /* unspecified */,
	    nofollow = /* unspecified */

	};

	This  type represents available options that control the behavior of the
     function
	std::filesystem::permissions().

	perm_options satisfies the requirements of BitmaskType (which means  the
     bitwise
	operators operator&, operator|, operator^, operator~, operator&=, opera-
     tor|=, and
	operator^= are defined for this type).

Member constants
	At most one of add, remove, replace may be present, otherwise the behav-
     ior of the
	permissions function is undefined.

	Member constant 			      Meaning
	replace 	 Permissions will be completely replaced by the argument
     to
			permissions() (default behavior)
	add		Permissions will be replaced by the bitwise  OR  of  the
     argument and
			the current permissions
	remove		 Permissions  will be replaced by the bitwise AND of the
     negated
			argument and current permissions
	nofollow	Permissions will  be  changed  on  the	symlink  itself,
     rather than on
			the file it resolves to

Example
     // Run this code

      #include <filesystem>
      #include <fstream>
      #include <iostream>

      void demo_perms(std::filesystem::perms p)
      {
	  using std::filesystem::perms;
	  auto show = [=](char op, perms perm)
	  {
	      std::cout << (perms::none == (perm & p) ? '-' : op);
	  };
	  show('r', perms::owner_read);
	  show('w', perms::owner_write);
	  show('x', perms::owner_exec);
	  show('r', perms::group_read);
	  show('w', perms::group_write);
	  show('x', perms::group_exec);
	  show('r', perms::others_read);
	  show('w', perms::others_write);
	  show('x', perms::others_exec);
	  std::cout << '\n';
      }

      int main()
      {
	  std::ofstream("test.txt"); // create file

	  std::cout << "Created file with permissions: ";
	  demo_perms(std::filesystem::status("test.txt").permissions());

	  std::filesystem::permissions(
	      "test.txt",
	      std::filesystem::perms::owner_all 	 |	   std::filesys-
     tem::perms::group_all,
	      std::filesystem::perm_options::add
	  );

	  std::cout << "After adding u+rwx and g+rwx:  ";
	  demo_perms(std::filesystem::status("test.txt").permissions());

	  std::filesystem::remove("test.txt");
      }

Possible output:
      Created file with permissions: rw-r--r--
      After adding u+rwx and g+wrx:  rwxrwxr--

See also
	permissions modifies file access permissions
	(C++17)     (function)
	perms	    identifies file system permissions
	(C++17)     (enum)

http://cppreference.com 	   2024.06.10	   std::filesy...perm_options(3)
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