Std::filesystem::is_character_file (3) Linux Manual Page

std::filesystem::is_character_file – std::filesystem::is_character_file

Synopsis

Defined in header<filesystem>

    bool is_character_file(std::filesystem::file_status s) noexcept;
(1)(since C++ 17)

    bool is_character_file(const std::filesystem::path &p);
(2)(since C++ 17)

    bool is_character_file(const std::filesystem::path &p, std::error_code &ec) noexcept;

Checks if the given file status or path corresponds to a character special file, as if determined by POSIX S_ISCHR. Examples of character special files are character devices such as /dev/null, /dev/tty, /dev/audio, or /dev/nvram on Linux.
1) Equivalent to s.type() == file_type::character.
2) Equivalent to is_character_file(status(p)) or is_character_file(status(p, ec)) respectively

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 character device, false otherwise. The non-throwing overload returns false if an error occurs.

Exceptions

2) The overload that does not take a std::error_code& parameter throws 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. The overload taking a std::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. Any overload not marked noexcept may throw std::bad_alloc if memory allocation fails.

Example

// Run this code

#include <iostream>

#include <fstream>

#include <cstdio>

#include <cstring>

#include <filesystem>

#include <unistd.h>

#include <sys/socket.h>

#include <sys/un.h>

#include <sys/stat.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");
    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::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
    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

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

std::filesystem::is_character_file (3) Linux Manual Page