std::filesystem::status, std::filesystem::symlink_status

Defined in header `<filesystem>`
std::filesystem::file_status status( const std::filesystem::path& p );	(1)	(since C++17)
std::filesystem::file_status status( const std::filesystem::path& p, std::error_code& ec ) noexcept;	(2)	(since C++17)
std::filesystem::file_status symlink_status( const std::filesystem::path& p );	(3)	(since C++17)
std::filesystem::file_status symlink_status( const std::filesystem::path& p, std::error_code& ec ) noexcept;	(4)	(since C++17)

1,2) Determines the type and attributes of the filesystem object identified by p as if by POSIX stat (symlinks are followed to their targets). In the following description, prms is the result of (m & perms::mask), where m is obtained as if by taking st_mode from the POSIX struct stat and converting it to the type std::filesystem::perms.

If p is a regular file (as if by POSIX S_ISREG), returns file_status(file_type::regular, prms).
If p is a directory (as if by POSIX S_ISDIR), returns file_status(file_type::directory, prms).
If p is a block special file (as if by POSIX S_ISBLK), returns file_status(file_type::block, prms).
If p is a character special file (as if by POSIX S_ISCHR), returns file_status(file_type::character, prms).
If p is a fifo or pipe file (as if by POSIX S_ISFIFO), returns file_status(file_type::fifo, prms).
If p is a socket (as if by POSIX S_ISSOCK), returns file_status(file_type::socket, prms).
If p has an implementation-defined file type, returns file_status(file_type::A, prms) where A is the implementation-defined file_type constant for that type.
If p does not exist, returns file_status(file_type::not_found).
If p exists but file attributes cannot be determined, e.g. due to lack of permissions, returns file_status(file_type::unknown).
If errors prevent even knowing whether p exists, the non-throwing overload sets ec and returns file_status(file_type::none), and the throwing overload throws filesystem_error.
Otherwise, returns file_status(file_type::unknown, prms).

3,4) Same as (1,2) except that the behavior is as if the POSIX lstat is used (symlinks are not followed):

If p is a symlink, returns file_status(file_type::symlink).

Parameters

p	-	path to examine
ec	-	out-parameter for error reporting in the non-throwing overload

Return value

The file status (a filesystem::file_status object).

Exceptions

Any overload not marked noexcept may throw std::bad_alloc if memory allocation fails.

1,3) Throws std::filesystem::filesystem_error on underlying OS API errors, constructed with p as the first path argument and the OS error code as the error code argument.

2,4) 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.

Notes

The information provided by this function is usually also provided as a byproduct of directory iteration, and may be obtained by the member functions of filesystem::directory_entry. During directory iteration, calling status again is unnecessary.

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::directory_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

Compiler support
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Standard library
Standard library headers
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Feature test macros (C++20)
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Concepts library (C++20)
Metaprogramming library (C++11)
Diagnostics library
General utilities library
Strings library
Containers library
Iterators library
Ranges library (C++20)
Algorithms library
Numerics library
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Filesystem library (C++17)
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Concurrency support library (C++11)
Execution support library (C++26)
Technical specifications
Symbols index
External libraries

file_status (C++17)	represents file type and permissions (class)
status_known (C++17)	checks whether file status is known (function)
is_block_file (C++17)	checks whether the given path refers to block device (function)
is_character_file (C++17)	checks whether the given path refers to a character device (function)
is_directory (C++17)	checks whether the given path refers to a directory (function)
is_fifo (C++17)	checks whether the given path refers to a named pipe (function)
is_other (C++17)	checks whether the argument refers to an other file (function)
is_regular_file (C++17)	checks whether the argument refers to a regular file (function)
is_socket (C++17)	checks whether the argument refers to a named IPC socket (function)
is_symlink (C++17)	checks whether the argument refers to a symbolic link (function)
exists (C++17)	checks whether path refers to existing file system object (function)
statussymlink_status	status of the file designated by this directory entry; status of the file/symlink designated by this directory entry (public member function of `std::filesystem::directory_entry`)