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std::experi...::is_symlink(3)  C++ Standard Libary std::experi...::is_symlink(3)

NAME
     std::experimental::filesystem::is_symlink	 -   std::experimental::filesys-
     tem::is_symlink

Synopsis
	Defined in header <experimental/filesystem>
	bool is_symlink( file_status s );		  (1) (filesystem TS)
	bool is_symlink( const path& p );		  (2) (filesystem TS)
	bool is_symlink( const path& p, error_code& ec );

	Checks if the given file status or path corresponds to a symbolic  link,
     as if
	determined by the POSIX S_IFLNK.

	1) Equivalent to s.type() == file_type::symlink.
	2) Equivalent to is_symlink(status(p)) or is_symlink(status(p, ec)).

Parameters
	s  - file status to check
	p  - path to examine
	ec - out-parameter for error reporting in the non-throwing overload

Return value
	true  if  the file indicated by p or if the type indicated s refers to a
     symbolic
	link. The non-throwing overload returns false if an error occurs.

Exceptions
	1)
	noexcept specification:
	noexcept

	2) The overload that does  not	take  an  error_code&  parameter  throws
     filesystem_error
	on  underlying	OS  API errors, constructed with p as the first argument
     and the OS
	error code as the error code argument. std::bad_alloc may be  thrown  if
     memory
	allocation  fails.  The overload taking an error_code& parameter sets it
     to the OS API
	error code if an OS API call fails, and executes ec.clear() if no errors
     occur. This
	overload has
	noexcept specification:
	noexcept

Notes
	The information provided by this function is usually also provided as  a
     byproduct of
	directory iteration. During directory iteration, calling is_symlink(*it-
     erator) is
	less efficient than is_symlink(iterator->status()).

Example
     // Run this code

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

      namespace fs = std::experimental::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");
	  std::ofstream("sandbox/file"); // create regular file
	  fs::create_directory("sandbox/dir");
	  mkfifo("sandbox/pipe", 0644);
	  struct 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, (struct sockaddr*)&addr, sizeof addr);
	  fs::create_symlink("file", "sandbox/symlink");

	  // 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
	  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
			  (function)
	file_status	  represents file type and permissions
			  (class)
	status_known	  checks whether file status is known
			  (function)
	is_block_file	  checks whether the given path refers to block device
			  (function)
	is_character_file  checks  whether  the given path refers to a character
     device
			  (function)
	is_directory	  checks whether the given path refers to a directory
			  (function)
	is_fifo 	  checks whether the given path refers to a named pipe
			  (function)
	is_other	  checks whether the argument refers to an other file
			  (function)
	is_regular_file   checks whether the argument refers to a regular file
			  (function)
	is_socket	  checks whether the argument  refers  to  a  named  IPC
     socket
			  (function)
	exists		  checks whether path refers to existing file system ob-
     ject
			  (function)
			  cached status of the file designated by this directory
     entry
	status		   cached  symlink_status of the file designated by this
     directory
	symlink_status	  entry
			  (public member function of
			  std::experimental::filesystem::directory_entry)

Categories:
	  * Noindexed pages
	  * unconditionally noexcept

Hidden categories:
	  * Pages with unreviewed unconditional noexcept template
	  * Pages with unreviewed noexcept template

http://cppreference.com 	   2024.06.10	   std::experi...::is_symlink(3)
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