fcitx5

TLDR

Start fcitx5 input method daemon

$ fcitx5

Start in daemon mode (background)

$ fcitx5 -d

Start with verbose output for debugging

$ fcitx5 -v

Replace an existing fcitx5 instance

$ fcitx5 -r

Display version information

$ fcitx5 --version

SYNOPSIS

fcitx5 [-drvh] [--replace] [--verbose]

Fcitx5 is a flexible input method framework for Unix-like systems, primarily used for entering Chinese, Japanese, Korean (CJK), and other languages requiring complex input methods. It is the successor to Fcitx and features a modular, plugin-based architecture.
The framework provides a lightweight core with additional language support via addons. Input method engines for various languages can be installed separately (e.g., fcitx5-chinese-addons for Chinese, fcitx5-anthy for Japanese, fcitx5-hangul for Korean).
For proper operation, environment variables should be set in the desktop session:

$ XMODIFIERS=@im=fcitx
GTK_IM_MODULE=fcitx
QT_IM_MODULE=fcitx

Fcitx5 supports both X11 and Wayland, with native Wayland text-input protocol support for better integration.

PARAMETERS

-d, --daemon

Run as a background daemon.

-r, --replace

Replace an existing fcitx5 instance.

-v, --verbose

Enable verbose output for debugging.

-h, --help

Display help message.

--version

Display version information.

CAVEATS

Different desktop environments may require different configuration methods for autostart and environment variables. On Wayland, the native text-input protocol is preferred over legacy input method modules. Some applications may require the GTK or Qt IM modules for proper input method support.

HISTORY

Fcitx (Flexible Context Input X) was originally developed for Chinese input on Linux. Fcitx5 is a complete rewrite released under LGPL-2.1+, offering improved architecture, better Wayland support, and enhanced extensibility. The modular design allows input methods, themes, and features to be added as independent plugins.