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

std::filesystem::space – std::filesystem::space

Synopsis

Defined in header<filesystem>

    std::filesystem::space_info space(const std::filesystem::path &p);

std::filesystem::space_info space(const std::filesystem::path &p, (since C++ 17)

                                                                      std::error_code &ec) noexcept;

Determines the information about the filesystem on which the pathname p is located, as if by POSIX statvfs
Populates and returns an object of type space_info, set from the members of the POSIX struct statvfs as follows
* space_info.capacity is set as if by f_blocks*f_frsize
* space_info.free is set to f_bfree*f_frsize
* space_info.available is set to f_bavail*f_frsize
* Any member that could not be determined is set to static_cast<uintmax_t>(-1)
The non-throwing overload sets all members to static_cast<uintmax_t>(-1) on error.

Parameters

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

Return value

The filesystem information (a space_info object)

Exceptions

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.

Notes

space_info.available may be less than space_info.free

Example

// Run this code

#include <iostream>

#include <filesystem>

namespace fs = std::filesystem;

int main()

{
    fs::space_info devi = fs::space("/dev/null");
    fs::space_info tmpi = fs::space("/tmp");
    std::cout << ".        Capacity       Free      Available\n"
              << "/dev:   " << devi.capacity << "   "
              << devi.free << "   " << devi.available << '\n'
              << "/tmp: " << tmpi.capacity << " "
              << tmpi.free << " " << tmpi.available << '\n';
}

Possible output:

  . Capacity Free Available
  /dev: 4175114240 4175110144 4175110144
  /tmp: 420651237376 411962273792 390570749952

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