Flux

Flux is a GTK4/Libadwaita file manager for Linux, written in Rust. I wanted something that opens instantly, looks at home on GNOME and Wayland, and can be driven from the keyboard. It does that, and it does it faster than the other GUI file managers I tried.

The icons shown in the screenshot are from WhiteSur Icon Theme (GPL-3.0).

Startup time

Cold start on a Ryzen 5 5600X, mean of 10 runs:

File manager	Startup
Flux	105 ms
PCManFM	134 ms
SpaceFM	169 ms
Thunar	290 ms
Nautilus	743 ms

Features

• Archives behave like folders. Open zip, 7z, rar, tar, iso and deb files like any directory, with thumbnails and previews of what's inside. Nothing gets extracted.
• Search that's already there. Type to filter the folder, press Ctrl+F for a search panel on the right, or start with : to search inside files. There is no index to build and no background service.
• Your servers and drives. SMB, SFTP, FTP, WebDAV, NFS, MTP and Google Drive, plus encrypted LUKS volumes.
• A terminal that follows you. Press F4, cd somewhere, and the file view goes with you.
• Show and hide from a keybind. flux-fm --toggle shows or hides the running window, --show brings it to the front and --hide tucks it away. With no window running, --toggle and --show start Flux and --hide does nothing, so one compositor shortcut is enough.
• Tags. Label files and find them again with #tag or Ctrl+Shift+T. Tags use the standard user.xdg.tags file attribute, so they stay with the file.
• A preview panel that keeps up. Images, video, audio and PDFs show as you move through files. F11 goes wide, and videos even play right in the grid. Code (with syntax highlighting), Markdown, CSV tables, Office documents and fonts preview too. Previews only show what's inside a file, editing is left to your preferred app.

• Icons and covers. Change the icon for a file type, a single file or a folder with any image. Use it to give videos, games and music their own cover art, and set whole batches from the command line.

Grid mode vs list mode

Grid mode renders each item as a card. It is best for folders with a moderate number of items. Flux automatically switches to list mode for folders with more items than the Auto List Mode Threshold (default 300), which stays responsive with several thousand items.

The threshold is configured in Settings → Behavior → Auto List Mode Threshold. Set it to 0 to disable the auto-switch and always use the mode chosen in the header.

Reference numbers

Same folder, same hardware, same session, 13,209 items (50 GB of images).

File manager	Behavior
Flux (grid mode)	Scrollbar fine, ~50% of one core on drag, hover slightly slow
Flux (list mode)	No lag, ~30% of one CPU core on scrollbar drag
Nautilus (grid mode)	Crashes: VK_ERROR_OUT_OF_HOST_MEMORY and file-descriptor exhaustion
Nautilus (list mode)	Uses more than 3 CPU cores to drag the scrollbar
Thunar (grid mode)	Laggy scrollbar, ~60% CPU on drag alone, saturates all cores on a full drag
Thunar (grid mode)	Scrollbar thumb desyncs and stops tracking position at large item counts
Thunar (list mode)	Laggy scrollbar, ~40% CPU on drag alone

Install

Flux needs GTK 4 and libadwaita 1.5 or newer, so Debian 12 and Ubuntu 22.04 are too old.

Flatpak (FlatPark)

Flux is available on FlatPark, a community-maintained Flatpak remote. This version runs with full host system access so Flux can manage your files natively.

flatpak remote-add --if-not-exists flatpark https://dl.flatpark.org/flatpark.flatpakrepo
flatpak install flatpark io.github.killown.flux

Arch (AUR)

yay -S flux-filemanager-git

From source

Install the dependencies first.

Debian / Ubuntu:

sudo apt install build-essential pkg-config git gettext desktop-file-utils libadwaita-1-dev libgtk-4-dev libpango1.0-dev libgraphene-1.0-dev \
  libcairo2-dev libgdk-pixbuf-2.0-dev libpoppler-glib-dev ffmpeg imagemagick icoutils p7zip-full

Fedora:

sudo dnf install gcc make pkgconf-pkg-config git gettext desktop-file-utils libadwaita-devel gtk4-devel pango-devel graphene-devel cairo-devel \
  gdk-pixbuf2-devel poppler-glib-devel ffmpeg ImageMagick icoutils p7zip

Arch:

sudo pacman -S base-devel git gettext desktop-file-utils libadwaita gtk4 glib2 pango graphene cairo gdk-pixbuf2 poppler-glib \
  ffmpeg imagemagick icoutils ttf-nerd-fonts-symbols p7zip

Then build it:

git clone https://github.com/killown/flux.git
cd flux
cargo build --release
make install

make install installs for the current user into ~/.local. The binary is ~/.local/bin/flux-fm, so make sure that folder is in your PATH. It also copies the default menus and helper scripts and downloads the community themes (this needs git and a connection, and is skipped if you're offline).

The default right-click menu is a starting point. Some entries call tools such as alacritty, wl-clipboard, yt-dlp or Python with PyGObject, so edit menu.rs to match what you have installed.

The menu editor uses Nerd Font icons. Arch gets the font from the package above. On Debian, Ubuntu and Fedora, download SymbolsNerdFont-Regular.ttf into ~/.local/share/fonts and run fc-cache -f.

Network browsing needs gvfs plus a backend such as gvfs-smb or gvfs-sftp. LUKS needs cryptsetup and udisks2.

Themes

Flux includes a built-in theme engine. You can switch the GTK UI, the embedded terminal colors, and the Papirus folder icons simultaneously.

Available themes:

• blue (Classic)
• frost (Pastel Blue)
• forge (Warm Orange)
• cyan (Neon)
• obsidian (Stealth Black)
• monolith (High-Contrast Greyscale)
• crimson (Deep Burgundy)
• smoke (Industrial Grey)

Usage (Fish Shell)

To use the Fish shell theme switcher, symlink or copy the script to your Fish functions folder: cp scripts/flux-theme.fish ~/.config/fish/functions/

Then run: flux-theme blue

Shortcuts

Key	Action
Ctrl+L	Go to location
Ctrl+F	Search panel (right side)
Alt+Left / Alt+Right	Back / forward
F2	Rename
F4	Terminal
F5	Refresh
F8	Sidebar
F9	Context menu editor
F10	Preferences
F11	Wide preview
Ctrl+H	Hidden files
Ctrl+Z / Ctrl+Y	Undo / redo
Ctrl+T	Edit tags
Ctrl+Middle Click	Open folder in new window

F1 shows the rest.

Customization

Flux is built to be changed:

• Settings live in ~/.config/flux/config.toml, and most of them are in Preferences (F10).
• Style the whole interface with CSS in ~/.config/flux/style.css. It loads on top of the theme and reloads when you save.
• Install themes into ~/.local/share/flux/themes. Community themes come from flux-themes.
• Use any image as the window or sidebar background from the right-click menu.
• Rearrange the sidebar: drag and drop to move items and create new sections.
• Move the window controls to either side.
• Hide the sidebar, header bar and status bar (F8, F6, F7), or start with --no-sidebar, --no-header or --no-statusbar.
• Hide file extensions.
• Set a custom icon for a single file or folder, or for every file with a given extension.
• Set or reset icons in bulk from the command line, with one TARGET<TAB>IMAGE pair per line:

printf '%s\t%s\n' ~/Videos ~/icons/video.svg ~/Music ~/icons/music.svg | flux-fm --set-icons-stdin

• Edit the right-click menus by hand in ~/.config/flux/menu.rs, or use the editor on F9. A second menu on Ctrl+Right-Click changes with the file type, so the main menu can stay short:

"󰉋   Inspect Directory" => "directory", "builtin::inspect_dir"
"󰋜   Open With…"        => "all", "builtin::open_with_dialog"
"󰆴   Move to Trash"     => "all", "builtin::delete"

Under the hood

Rust, Relm4 and GTK4, Tokio and Rayon, Nucleo for fuzzy matching, the ignore crate for directory walking, and SQLite for tags. There are 600+ tests (sh tests.sh), and the parsers are fuzzed with libFuzzer.

Contributing

Pull requests are welcome. If the change is big, open an issue first. Please run the tests before sending it.

License

GPLv3