std::filesy...tory_symlink(3)

🎀 NAME 🎀

std::filesystem::create_symlink,std::filesystem::create_directory_symlink — std::filesystem::create_symlink,std::filesystem::create_directory_symlink, bestie. This page is filed as std::filesy...tory_symlink(3) in the C++ Standard Libary manual. Yes, that’s exactly how the manual name is spelled up top — keeping the facts intact 💅.

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✨ SYNOPSIS ✨

Defined in header <filesystem> — overloads (1) through (4) are all since C++17 💖.

Defined in header <filesystem>

void create_symlink( const std::filesystem::path& target,
                     const std::filesystem::path& link );  (1) (since C++17)

void create_symlink( const std::filesystem::path& target,
                     const std::filesystem::path& link,
                     std::error_code& ec ) noexcept;       (2) (since C++17)

void create_directory_symlink( const std::filesystem::path& target,
                               const std::filesystem::path& link );  (3) (since C++17)

void create_directory_symlink( const std::filesystem::path& target,
                               const std::filesystem::path& link,
                               std::error_code& ec ) noexcept;       (4) (since C++17)

Okay so what does it do? It creates a symbolic link named link with its target set to target, as if by POSIX symlink(): the pathname target may be invalid or non-existing. Literally no cap there — the thing you point at does not have to exist 🫶.

Some operating systems require symlink creation to identify that the link is to a directory. Portable code should use (3,4) to create directory symlinks rather than (1,2), even though there is no distinction on POSIX systems. That’s the vibe check for writing code that travels well 🌍.

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💅 PARAMETERS 💅

• target — path to point the symlink to, does not have to exist. Yes, it can be out here being imaginary 🦋.
• link — path of the new symbolic link.
• ec — out-parameter for error reporting in the non-throwing overload.

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🎁 RETURN VALUE 🎁

(none) — that’s it, no return value, periodt 💀.

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🔥 EXCEPTIONS 🔥

• Any overload not marked noexcept may throw std::bad_alloc if memory allocation fails. Memory said “not today” 😭.
• 1,3) Throws std::filesystem::filesystem_error on underlying OS API errors, constructed with target as the first path argument, link as the second 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. Cleanup slay ✨.

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🌸 NOTES 🌸

• Some operating systems do not support symbolic links at all or support them only for regular files. Rude, but true 💔.
• Some file systems do not support symbolic links regardless of the operating system, for example the FAT system used on some memory cards and flash drives.
• Like a hard link, a symbolic link allows a file to have multiple logical names. The presence of a hard link guarantees the existence of a file, even after the original name has been removed. A symbolic link provides no such assurance; in fact, the file named by the target argument need not exist when the link is created. A symbolic link can cross file system boundaries. It’s giving “no guarantees, only vibes” 🧚.

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🧪 EXAMPLE 🧪

// Run this code

#include <cassert>
#include <filesystem>
#include <iostream>
namespace fs = std::filesystem;

int main()
{
    fs::create_directories("sandbox/subdir");
    fs::create_symlink("target", "sandbox/sym1");
    fs::create_directory_symlink("subdir", "sandbox/sym2");

    for (auto it = fs::directory_iterator("sandbox"); it != fs::directory_iterator(); ++it)
        if (is_symlink(it->symlink_status()))
            std::cout << *it << "->" << read_symlink(*it) << '\n';

    assert(std::filesystem::equivalent("sandbox/sym2", "sandbox/subdir"));
    fs::remove_all("sandbox");
}

🌈 Possible output 🌈

"sandbox/sym1"->"target"
"sandbox/sym2"->"subdir"

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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)
• read_symlink — obtains the target of a symbolic link. (C++17) (function)
• create_hard_link — creates a hard link. (C++17) (function)

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That’s the whole page, bestie! Source: http://cppreference.com · version/date: 2024.06.10 · page: std::filesy...tory_symlink(3). Mwah 💋💖