Checking if a directory exists in Unix (system call)

user_448022 0
Viewed 64527

I am not able to find a solution to my problem online.

I would like to call a function in Unix, pass in the path of a directory, and know if it exists. opendir() returns an error if a directory does not exist, but my goal is not to actually open, check the error, close it if no error, but rather just check if a file is a directory or not.

Is there any convenient way to do that please?

exists directory unix c c++
5 Answers

Another simple way would be:

int check(unsigned const char type) {
    if(type == DT_REG)
        return 1;
    if(type == DT_DIR)
        return 0;
    return -1;
}

You can then pass struct dirent* object's d_type to check function.

If check returns 1, then that path points to regular file.

If check returns 0, then that path points to a directory.

Otherwise, it is neither a file or a directory (it can be a Block Device/Symbolic Link, etc..)

user_42875030

C++17

Use std::filesystem::is_directory:

#include <filesystem>

void myFunc(const std::filesystem::path& directoryPath_c)
{
    if (std::filesystem::is_directory(directoryPath_c)) {
    //if (std::filesystem::exists(directoryPath_c)) { // Alternative*
        // do something.
    }
}

Or in its noexept version:

#include <filesystem>

void myFunc(const std::filesystem::path& directoryPath_c)
{
    std::error_code ec{};
    if (std::filesystem::is_directory(directoryPath_c, ec)) {
    //if (std::filesystem::exists(directoryPath_c, ec)) { // An alternative*
        // do something.
    }
}
  • The disadvantage of the alternative is, that if directoryPath_c exists as a regular-file, std::filesystem::exists(directoryPath_c) returns true despite the folder does not exists.
user_173675600
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