Std::experimental::filesystem::is_symlink (3) Linux Manual Page

std::experimental::filesystem::is_symlink – std::experimental::filesystem::is_symlink

Synopsis

Defined in header<experimental / filesystem>

    bool is_symlink(file_status s);
(1)(filesystem TS)

    bool is_symlink(const path &p);
(2)(filesystem TS)

    bool is_symlink(const path &p, error_code &ec);

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) Equivalent to is_symlink(status(p)) or is_symlink(status(p, ec)).

Parameters

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

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.

Exceptions

1)
noexcept specification:
noexcept
2,3) The overload that does not take a error_code& parameter throws filesystem_error on underlying OS API errors, constructed with p as the first argument and the OS error code as the error code argument. std::bad_alloc may be thrown if memory allocation fails. The overload taking a 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. This overload has
noexcept specification:
noexcept

Notes

The information provided by this function is usually also provided as a byproduct of directory iteration. During directory iteration, calling is_symlink(*iterator) is less efficient than is_symlink(iterator->status())

Example

// Run this code

#include <iostream>

#include <fstream>

#include <cstdio>

#include <cstring>

#include <experimental/filesystem>

#include <unistd.h>

#include <sys/socket.h>

#include <sys/un.h>

#include <sys/stat.h>
namespace fs = std::experimental::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");
    std::ofstream("sandbox/file"); // create regular file
    fs::create_directory("sandbox/dir");
    mkfifo("sandbox/pipe", 0644);
    struct 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, (struct sockaddr *)&addr, sizeof addr);
    fs::create_symlink("file", "sandbox/symlink");
    // 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
    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

                  determines file attributes
status determines file attributes, checking the symlink target
symlink_status (function)
                  represents file type and permissions
file_status (class)
                  checks whether file status is known
status_known (function)
                  checks whether the given path refers to block device
is_block_file (function)
                  checks whether the given path refers to a character device
is_character_file (function)
                  checks whether the given path refers to a directory
is_directory (function)
                  checks whether the given path refers to a named pipe
is_fifo (function)
                  checks whether the argument refers to an other file
is_other (function)
                  checks whether the argument refers to a regular file
is_regular_file (function)
                  checks whether the argument refers to a named IPC socket
is_socket (function)
                  checks whether path refers to existing file system object
exists (function)
                  cached status of the file designated by this directory entry
status cached symlink_status of the file designated by this directory entry
symlink_status (public member function of std::experimental::filesystem::directory_entry)

std::experimental::filesystem::is_symlink (3) Linux Manual Page