std::filesystem::is_symlink
std::filesystem::is_symlink
| Defined in header | | |
|---|---|---|
| bool is_symlink( std::filesystem::file_status s | (1) | (since C++17) |
| bool is_symlink( const std::filesystem::path& p bool is_symlink( const std::filesystem::path& p, std::error_code& ec | (2) | (since C++17) |
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 std::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 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. This overload has
noexcept specification:
noexcept
Example
#include <iostream>
#include <fstream>
#include <cstdio>
#include <cstring>
#include <filesystem>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/stat.h>
namespace fs = std::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
See also
| statussymlink_status (C++17)(C++17) | determines file attributesdetermines file attributes, checking the symlink target (function) |
|---|---|
| file_status (C++17) | represents file type and permissions (class) |
| status_known (C++17) | checks whether file status is known (function) |
| is_block_file (C++17) | checks whether the given path refers to block device (function) |
| is_character_file (C++17) | checks whether the given path refers to a character device (function) |
| is_directory (C++17) | checks whether the given path refers to a directory (function) |
| is_fifo (C++17) | checks whether the given path refers to a named pipe (function) |
| is_other (C++17) | checks whether the argument refers to an other file (function) |
| is_regular_file (C++17) | checks whether the argument refers to a regular file (function) |
| is_socket (C++17) | checks whether the argument refers to a named IPC socket (function) |
| exists (C++17) | checks whether path refers to existing file system object (function) |
| statussymlink_status | status of the file designated by this directory entrysymlink_status of the file designated by this directory entry (public member function of std::filesystem::directory_entry) |
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