From Get docs


Defined in header <filesystem>
enum class perms;
(since C++17)

This type represents file access permissions. perms satisfies the requirements of BitmaskType (which means the bitwise operators operator&, operator|, operator^, operator~, operator&=, operator|=, and operator^= are defined for this type).

Access permissions model POSIX permission bits, and any individual file permissions (as reported by status) are a combination of some of the following bits:

Member constants

Member constant Value (octal) POSIX equivalent Meaning
none ​0​ no permission bits are set
owner_read 0400 S_IRUSR File owner has read permission
owner_write 0200 S_IWUSR File owner has write permission
owner_exec 0100 S_IXUSR File owner has execute/search permission
owner_all 0700 S_IRWXU

File owner has read, write, and execute/search permissions Equivalent to owner_read | owner_write | owner_exec.

group_read 040 S_IRGRP The file's user group has read permission
group_write 020 S_IWGRP The file's user group has write permission
group_exec 010 S_IXGRP The file's user group has execute/search permission
group_all 070 S_IRWXG

The file's user group has read, write, and execute/search permissions Equivalent to group_read | group_write | group_exec.

others_read 04 S_IROTH Other users have read permission
others_write 02 S_IWOTH Other users have write permission
others_exec 01 S_IXOTH Other users have execute/search permission
others_all 07 S_IRWXO

Other users have read, write, and execute/search permissions Equivalent to others_read | others_write | others_exec.

all 0777

All users have read, write, and execute/search permissions Equivalent to owner_all | group_all | others_all.

set_uid 04000 S_ISUID Set user ID to file owner user ID on execution
set_gid 02000 S_ISGID Set group ID to file's user group ID on execution
sticky_bit 01000 S_ISVTX Implementation-defined meaning, but POSIX XSI specifies that when set on a directory, only file owners may delete files even if the directory is writeable to others (used with /tmp)
mask 07777

All valid permission bits. Equivalent to all | set_uid | set_gid | sticky_bit.

Additionally, the following constants of this type are defined, which do not represent permissions:

Member constant Value (hex) Meaning
unknown 0xFFFF Unknown permissions (e.g. when file_status is created without permissions)


Permissions may not necessarily be implemented as bits, but they are treated that way conceptually.

Some permission bits may be ignored on some systems, and changing some bits may automatically change others (e.g. on platforms without owner/group/all distinction, setting any of the three write bits set all three).


#include <fstream>
#include <bitset>
#include <iostream>
#include <filesystem>
namespace fs = std::filesystem;
void demo_perms(fs::perms p)
    std::cout << ((p & fs::perms::owner_read) != fs::perms::none ? "r" : "-")
              << ((p & fs::perms::owner_write) != fs::perms::none ? "w" : "-")
              << ((p & fs::perms::owner_exec) != fs::perms::none ? "x" : "-")
              << ((p & fs::perms::group_read) != fs::perms::none ? "r" : "-")
              << ((p & fs::perms::group_write) != fs::perms::none ? "w" : "-")
              << ((p & fs::perms::group_exec) != fs::perms::none ? "x" : "-")
              << ((p & fs::perms::others_read) != fs::perms::none ? "r" : "-")
              << ((p & fs::perms::others_write) != fs::perms::none ? "w" : "-")
              << ((p & fs::perms::others_exec) != fs::perms::none ? "x" : "-")
              << '\n';
int main()
    std::ofstream("test.txt"); // create file
    std::cout << "Created file with permissions: ";
                    fs::perms::owner_all | fs::perms::group_all,
    std::cout << "After adding o+rwx and g+rwx:  ";

Possible output:

Created file with permissions: rw-r--r--
After adding o+rwx and g+wrx:  rwxrwxr--

See also


determines file attributes

determines file attributes, checking the symlink target


modifies file access permissions


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