To use fcitx to input text in Arch Linux, you will need to first install the necessary packages. You can do this by running the following command in the terminal:
sudo pacman -S fcitx fcitx-gtk2 fcitx-gtk3 fcitx-qt4 fcitx-qt5 fcitx-configtool
This will install fcitx and various input method modules for different graphical toolkits. After the installation is complete, you can launch the fcitx configuration tool by running the fcitx-configtool command in the terminal. From the configuration tool, you can add and activate the input method that you want to use.
Once you have set up your input method, you can switch to fcitx by setting the GTK_IM_MODULE and QT_IM_MODULE environment variables to “fcitx”. You can do this by adding the following lines to your .bashrc file:
export GTK_IM_MODULE=fcitx
export QT_IM_MODULE=fcitx
After adding these lines, you can log out and log back in (or restart your terminal) for the changes to take effect. Now you should be able to use your desired input method with fcitx as your input method framework.