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std::filesystem::is_fifo(3)    C++ Standard Libary   std::filesystem::is_fifo(3)

NAME
     std::filesystem::is_fifo - std::filesystem::is_fifo

Synopsis
	Defined in header <filesystem>
	bool  is_fifo(	std::filesystem::file_status s ) noexcept;	     (1)
     (since C++17)
	bool is_fifo( const std::filesystem::path& p  );		     (2)
     (since C++17)
	bool  is_fifo(	const std::filesystem::path& p, std::error_code& ec  (3)
     (since C++17)
	) noexcept;

	Checks if the given file status or path corresponds to a  FIFO	or  pipe
     file as if
	determined by POSIX S_ISFIFO.

	1) Equivalent to s.type() == file_type::fifo.
	2,3)  Equivalent to is_fifo(status(p)) or is_fifo(status(p, ec)) respec-
     tively.

Parameters
	s  - file status to check
	p  - path to query
	ec - error code to modify in case of errors

Return value
	true if the file indicated by p or if the type indicated s refers  to  a
     FIFO pipe,
	false otherwise. The non-throwing overload returns false if an error oc-
     curs.

Exceptions
	Any  overload not marked noexcept may throw std::bad_alloc if memory al-
     location
	fails.

	2,3) Sets a std::error_code& parameter to the OS API error code if an OS
     API call
	fails, and executes ec.clear() if no errors occur.

Example
     // Run this code

      #include <cstdio>
      #include <cstring>
      #include <filesystem>
      #include <fstream>
      #include <iostream>
      #include <sys/socket.h>
      #include <sys/stat.h>
      #include <sys/un.h>
      #include <unistd.h>

      namespace fs = std::filesystem;

      void demo_status(const fs::path& p, fs::file_status s)
      {
	  std::cout << p;
	  // alternative: switch(s.type()) { case fs::file_type::regular: ...}
	  if (fs::is_regular_file(s))
	      std::cout << " is a regular file\n";
	  if (fs::is_directory(s))
	      std::cout << " is a directory\n";
	  if (fs::is_block_file(s))
	      std::cout << " is a block device\n";
	  if (fs::is_character_file(s))
	      std::cout << " is a character device\n";
	  if (fs::is_fifo(s))
	      std::cout << " is a named IPC pipe\n";
	  if (fs::is_socket(s))
	      std::cout << " is a named IPC socket\n";
	  if (fs::is_symlink(s))
	      std::cout << " is a symlink\n";
	  if (!fs::exists(s))
	      std::cout << " does not exist\n";
      }

      int main()
      {
	  // create files of different kinds
	  fs::create_directory("sandbox");
	  fs::create_directory("sandbox/dir");
	  std::ofstream{"sandbox/file"}; // create regular file
	  fs::create_symlink("file", "sandbox/symlink");

	  mkfifo("sandbox/pipe", 0644);
	  sockaddr_un addr;
	  addr.sun_family = AF_UNIX;
	  std::strcpy(addr.sun_path, "sandbox/sock");
	  int fd = socket(PF_UNIX, SOCK_STREAM, 0);
	  bind(fd, reinterpret_cast<sockaddr*>(&addr), sizeof addr);

	  // demo different status accessors
	  for  (auto  it{fs::directory_iterator("sandbox")};  it  !=  fs::direc-
     tory_iterator(); ++it)
	      demo_status(*it,	it->symlink_status()); // use cached status from
     directory entry
	  demo_status("/dev/null", fs::status("/dev/null")); // direct calls  to
     status
	  demo_status("/dev/sda", fs::status("/dev/sda"));
	  demo_status("sandbox/no", fs::status("/sandbox/no"));

	  // cleanup (prefer std::unique_ptr-based custom deleters)
	  close(fd);
	  fs::remove_all("sandbox");
      }

Possible output:
      "sandbox/file" is a regular file
      "sandbox/dir" is a directory
      "sandbox/pipe" is a named IPC pipe
      "sandbox/sock" is a named IPC socket
      "sandbox/symlink" is a symlink
      "/dev/null" is a character device
      "/dev/sda" is a block device
      "sandbox/no" does not exist

See also
	status		  determines file attributes
	symlink_status	   determines file attributes, checking the symlink tar-
     get
	(C++17) 	  (function)
	(C++17)
	file_status	  represents file type and permissions
	(C++17) 	  (class)
	status_known	  checks whether file status is known
	(C++17) 	  (function)
	is_block_file	  checks whether the given path refers to block device
	(C++17) 	  (function)
	is_character_file checks whether the given path refers	to  a  character
     device
	(C++17) 	  (function)
	is_directory	  checks whether the given path refers to a directory
	(C++17) 	  (function)
	is_other	  checks whether the argument refers to an other file
	(C++17) 	  (function)
	is_regular_file   checks whether the argument refers to a regular file
	(C++17) 	  (function)
	is_socket	   checks  whether  the  argument  refers to a named IPC
     socket
	(C++17) 	  (function)
	is_symlink	  checks whether the argument refers to a symbolic link
	(C++17) 	  (function)
	exists		  checks whether path refers to existing file system ob-
     ject
	(C++17) 	  (function)
			  checks whether the directory entry refers to	a  named
     pipe
	is_fifo 	   (public  member  function  of std::filesystem::direc-
     tory_entry)

http://cppreference.com 	   2024.06.10	     std::filesystem::is_fifo(3)
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