NAME¶

std::filesystem::create_symlink,std::filesystem::create_directory_symlink - std::filesystem::create_symlink,std::filesystem::create_directory_symlink

Synopsis¶

Defined in header <filesystem>
void create_symlink( const std::filesystem::path& target,

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

std::error_code& ec ) noexcept;
void create_directory_symlink( const std::filesystem::path&
target,

const std::filesystem::path& link );
void create_directory_symlink( const std::filesystem::path& (2) (since C++17)
target,
const std::filesystem::path& link,

std::error_code& ec ) noexcept;

Creates a symbolic link link with its target set to target as if by POSIX symlink():
the pathname target may be invalid or non-existing.

Some operating systems require symlink creation to identify that the link is to a
directory. Portable code should use (2) to create directory symlinks rather than
(1), even though there is no distinction on POSIX systems.

Parameters¶

target - path to point the symlink to, does not have to exist
link - path of the new symbolic link
ec - out-parameter for error reporting in the non-throwing overload

Return value¶

(none)

Exceptions¶

The overload that does not take a std::error_code& parameter throws
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. 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.

Notes¶

Some operating systems do not support symbolic links at all or support them only for
regular files.

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.

Example¶

// Run this code

#include <iostream>
#include <filesystem>
#include <cassert>
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"

See also¶

status determines file attributes
symlink_status determines file attributes, checking the symlink target
(C++17) (function)
(C++17)
read_symlink obtains the target of a symbolic link
(C++17) (function)
create_hard_link creates a hard link
(C++17) (function)