Preview Files in Ubuntu: Quick Guide
To preview files in Ubuntu without opening them, you can use the built-in file manager (Files, also called Nautilus) with the preview feature enabled, or use a dedicated tool like GNOME Sushi for quick previews. This guide explains how to set up and use file previews in Ubuntu, covering the built-in options, third-party tools, and troubleshooting common issues.
What Is File Preview and Why Use It?
File preview lets you see the contents of a file—like an image, PDF, or text document—without launching a full application. It saves time when you’re browsing many files and only need a quick look. In Ubuntu, the default file manager can show thumbnails for images and videos in icon or list view, but for a more detailed preview (like a full-page PDF or a video player), you need a separate preview tool.
Built-in Preview Options in Ubuntu
The default file manager (Files) has a built-in preview pane that shows a thumbnail of the selected file. To enable it:
- Open Files (the folder icon in the dock).
- Press F6 or go to View → Sidebar → Preview.
- A sidebar appears on the right showing a preview of the selected file.
This preview works for images, PDFs, text files, and some video files, but it’s limited to a static thumbnail. For videos, it shows a single frame, not a playable preview.
Using GNOME Sushi for Quick Previews
GNOME Sushi is a lightweight tool that provides a full-screen preview when you press the spacebar on a selected file. It’s not installed by default in Ubuntu, but you can install it easily:
- Open a terminal (Ctrl+Alt+T).
- Run:
sudo apt install gnome-sushi - Once installed, restart the file manager (or log out and back in).
- Select any file and press the spacebar. A preview window pops up with the file’s content, and you can scroll through pages or play videos.
Sushi supports many formats: images, PDFs, audio, video, text, and even some office documents. It’s a quick, non-intrusive way to preview without opening a full app.
How to Choose the Right Preview Method
Your choice depends on what you need:
- Quick glance at images: The built-in thumbnail preview in Files is enough.
- Read a PDF without opening a reader: Use Sushi (spacebar) for a full-page view.
- Play a video clip: Sushi can play videos, but for longer videos you might prefer opening the default video player.
- Preview inside the file manager: Enable the Preview sidebar (F6) to see a thumbnail while browsing.
Common Problems and Fixes
Sometimes previews don’t work as expected. Here are typical issues and solutions:
- No preview appears when pressing spacebar: Make sure Sushi is installed and the file manager is restarted. If it still fails, check if the file type is supported (e.g., some proprietary formats may not preview).
- Thumbnails not showing in Files: Go to Files → Preferences → Search & Preview and ensure “Show thumbnails� is set to “Always� or “Only for local files.�
- Preview pane is too small: Drag the sidebar edge to resize it.
- Video preview stutters: This can happen with large files or missing codecs. Install Ubuntu restricted extras for common codecs:
sudo apt install ubuntu-restricted-extras.
Alternatives to Sushi and Built-in Preview
If you need more advanced previewing, consider these options:
- gThumb: A dedicated image viewer that also shows thumbnails and can browse folders quickly.
- Evince: The default PDF viewer, which has a continuous scroll preview mode.
- VLC: For video previews, VLC can play files directly, but it’s not a lightweight preview tool.
- Terminal-based: Tools like
chafaorviucan display images in the terminal, useful for SSH sessions.
Frequently Asked Questions
How do I preview files without opening them?
Install GNOME Sushi and press the spacebar on any file in the file manager. This gives a quick preview without launching a full application.
Why doesn’t the spacebar preview work?
Make sure Sushi is installed. If it is, check that the file type is supported. Some formats, like certain RAW images or proprietary office documents, may not preview.
Can I preview files in the terminal?
Yes, for text files you can use cat or less. For images, tools like chafa convert images to ANSI art. For PDFs, you can use pdftotext to extract text.
How do I enable thumbnails for all files?
In Files, go to Preferences → Search & Preview and set “Show thumbnails� to “Always.� This will generate thumbnails for images and videos, even on remote servers.
Is there a way to preview files in the file open dialog?
Most GTK applications use a built-in preview pane in the file chooser. Look for a split-view icon in the dialog, or press F6 to toggle it.