dir — Return file and folder metadata in MATLAB and RunMat.

dir returns metadata for files and folders. It supports current-directory listing, explicit paths, and wildcard patterns, returning MATLAB/RunMat-compatible struct fields such as name, folder, date, bytes, isdir, and datenum.

Syntax

listing = dir()
listing = dir(name)
listing = dir(folder, pattern)

Inputs

Returns

Errors

How dir works

• dir with no inputs returns the contents of the current folder (including . and ..).
• When you call dir without capturing the output, RunMat prints the listing in the REPL. Assigning the result to a variable suppresses the listing and returns the struct array.
• dir(path) accepts absolute or relative paths, character vectors, or string scalars. When the path names a directory, its contents are listed; when it names a file, metadata for that file alone is returned.
• dir(pattern) and dir(folder, pattern) support wildcard expansion with * and ?. Patterns are evaluated relative to the supplied folder or the current working directory.
• The returned struct fields mirror MATLAB:
• name: file or folder name.
• folder: absolute path to the containing folder.
• date: last-modified timestamp formatted as dd-MMM-yyyy HH:mm:ss in local time.
• bytes: file size in bytes (0 for directories and wildcard-only results).
• isdir: logical flag indicating whether the entry is a directory.
• datenum: serial date number compatible with MATLAB's datenum.
• Results are sorted using MATLAB-style ordering (case-insensitive on Windows, case-sensitive on Unix-like systems).
• Empty matches return a 0×1 struct array so idioms like isempty(dir("*.tmp")) continue working.
• Invalid arguments (numeric, logical, non-scalar string arrays) raise MATLAB-compatible diagnostics.

Does RunMat run dir on the GPU?

Because dir interacts with the host filesystem, it is executed entirely on the CPU. If an input argument resides on the GPU (for example, a scalar string created by another accelerated builtin), RunMat gathers it to host memory before expanding patterns. Acceleration providers do not implement hooks for dir, and the result always lives on the host.

GPU memory and residency

No. dir is an I/O-bound builtin and always operates on host data. Passing GPU-resident strings is supported, but RunMat gathers them automatically and there is no benefit to manually calling gpuArray.

Examples

List Files In The Current Folder

fid = fopen("README.md", "w"); fclose(fid);
mkdir("src");
listing = dir;
{listing.name}

Expected output:

{'.'}    {'..'}    {'README.md'}    {'src'}

List Only MATLAB Files Using Wildcards

fid = fopen("solver.m", "w"); fclose(fid);
fid = fopen("test_helper.m", "w"); fclose(fid);
scripts = dir("*.m");
cellstr({scripts.name})

Expected output:

{'solver.m'}
    {'test_helper.m'}

Capture Metadata For A Specific File

info = dir("data/results.csv");
info.bytes    % file size in bytes
info.isdir    % false

List The Contents Of A Specific Folder

mkdir("tmp");
fid = fopen(fullfile("tmp", "tmpfile.txt"), "w"); fclose(fid);
mkdir(fullfile("tmp", "subdir"));
tmp = dir(fullfile(pwd, "tmp"));
{tmp.name}'

Expected output:

'.'    '..'    'tmpfile.txt'    'subdir'

Combine Folder And Pattern Arguments

mkdir("assets");
fid = fopen(fullfile("assets", "logo.png"), "w"); fclose(fid);
fid = fopen(fullfile("assets", "splash.png"), "w"); fclose(fid);
images = dir("assets", "*.png");
{images.name}

Expected output:

{'logo.png'}    {'splash.png'}

Use Tilde Expansion For Home Directory

home_listing = dir("~")

Expected output:

home_listing(1).folder
ans =
    '/'

Handle Missing Matches Gracefully

if isempty(dir("*.cache"))
    disp("No cache files found.");
end

Expected output:

No cache files found.

Using dir with coding agents

Open a RunMat example with live inputs, then ask the agent to explain how dir changes the result.

FAQ

Related Io functions

Open-source implementation

Unlike proprietary runtimes, every RunMat function is open-source. Read exactly how dir is executed, line by line, in Rust.

• View the source for dir in Rust on GitHub
• Learn how the RunMat runtime works
• Found a bug? Open an issue with a minimal reproduction.

About RunMat

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