std::experimental::filesystem::is_symlink

Defined in header `<experimental/filesystem>`
bool is_symlink( file_status s );	(1)	(filesystem TS)
bool is_symlink( const path& p ); bool is_symlink( const path& p, error_code& ec );	(2)	(filesystem TS)

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) The overload that does not take an 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 an 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 <cstdio>
#include <cstring>
#include <experimental/filesystem>
#include <fstream>
#include <iostream>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/un.h>
#include <unistd.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

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

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