---
title: Opening a file
slug: opening-files
summary: The ways to open a Markdown file in Skimmark, and what the messages mean when a file will not open.
---

# Opening a file

Skimmark opens Markdown files: names ending in `.md` or `.markdown` (upper or lower case).

## Ways to open a file

- **Open button.** When no file is open, the window shows an **Open a file** button. Click it, or press Enter while it has focus.
- **Shortcut.** Press **Cmd+O** on Mac or **Ctrl+O** on Windows and Linux. You can pick several files at once.
- **Open menu (Mac and Linux).** Choose **File > Open…**. Windows has no menu yet; use Ctrl+O or the Open button.
- **Drag and drop.** Drag one or more Markdown files onto the window.
- **Terminal.** Type `skimmark notes.md` (Mac and Linux). See [The skimmark command](skimmark-command.md).
- **Double-click (Mac).** If Skimmark is the app for Markdown files, double-click a file in Finder.

Skimmark runs as one window. If it is already open, a new file opens there as a new tab, and the window comes to the front.

If a file is already open, opening it again switches to its tab. See [Tabs](tabs.md).

## When a file does not open

Messages show in a bar at the top of the window.

| Message | What it means |
|---|---|
| `File not found: <path>` | Nothing exists at that path. Check the spelling, or the folder you ran the command from. |
| `Not a Markdown file: <path>` | The file name does not end in `.md` or `.markdown`. |
| `Could not open <path>: <reason>` | The file exists but could not be read, for example because you do not have permission. |
| `This file is not valid UTF-8. Some characters may show as �.` | The file opened, but some bytes are not readable text. Skimmark shows them as � and never changes the file. |

## Example

Jane Doe keeps her notes in `~/Documents/doe-notes/`. She runs:

```sh
cd ~/Documents/doe-notes
skimmark plan.md ideas.md
```

Both files open as tabs in the same window.