std::filesy...::is_symlink(3)

💖 NAME

hey bestie, welcome to the std::filesy...::is_symlink(3) page — manual name: C++ Standard Libary (yes, that spelling is in the header, and we’re moving on 💀). The NAME line is literally std::filesystem::is_symlink — std::filesystem::is_symlink. same thing twice, iconic, no notes 💅.

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✨ Synopsis

It’s defined in header <filesystem>:

Defined in header <filesystem>
bool is_symlink( std::filesystem::file_status s ) noexcept;

(1) (since C++17)

bool is_symlink( const std::filesystem::path& p );

(2) (since C++17)

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

(3) (since C++17)

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), (3) Equivalent to is_symlink(symlink_status(p)) or is_symlink(symlink_status(p, ec)).

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🎀 Parameters

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

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🌸 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.

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💀 Exceptions

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

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

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🔥 Example

the page literally says // Run this code right before this beauty 👇

        #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

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👑 See also

• status — determines file attributes ((C++17), (function))
• symlink_status — determines file attributes, checking the symlink target ((C++17), (function))
• 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_fifo — checks whether the given path refers to a named pipe ((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))
• exists — checks whether path refers to existing file system object ((C++17), (function))
• is_symlink — checks whether the directory entry refers to a symbolic link ((C++17), public member function of std::filesystem::directory_entry)

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mwah 💋 — source/version: http://cppreference.com, date: 2024.06.10, page: std::filesy...::is_symlink(3) 🫶✨