You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.

7.4 KiB

Setting up a build environment for KOReader

These instructions are intended to build the emulator in Linux and macOS. Windows users are suggested to develop in a Linux VM or using the Windows Subsystem for Linux.

If you only want to work with Lua frontend stuff, you can grab the AppImage and run it with --appimage-extract.

You can skip most of the following instructions if desired, and use our premade Docker image instead. In that case the only requirements are Git and Docker. See the virtual development environment README for more information.

Note: If you want to use WSL then you'll need to export a sane PATH first, because Windows appends its own directories to it. You'll also need to install an XServer. If you need more info please read


To get and compile the source you must have patch, wget, unzip, git, cmake and luarocks installed, as well as a version of autoconf greater than 2.64. You also need nasm, ragel, and of course a compiler like gcc or clang.

Debian/Ubuntu and derivates

Install the prerequisites using APT:

sudo apt-get install build-essential git patch wget unzip \
gettext autoconf automake cmake libtool nasm ragel luarocks lua5.1 libsdl2-dev \
libssl-dev libffi-dev libsdl2-dev libc6-dev-i386 xutils-dev linux-libc-dev:i386 zlib1g:i386

Fedora/Red Hat

Install the libstdc++-static, SDL and SDL-devel packages using DNF:

sudo dnf install libstdc++-static SDL SDL-devel


Install the prerequisites using Homebrew:

brew install nasm ragel binutils coreutils libtool autoconf automake cmake makedepend \
sdl2 lua@5.1 luarocks gettext pkg-config wget gnu-getopt grep bison

You will also have to ensure Homebrew's gettext, gnu-getopt, bison & grep are in your path, e.g., via

export PATH="$(brew --prefix)/opt/gettext/bin:$(brew --prefix)/opt/gnu-getopt/bin:$(brew --prefix)/opt/bison/bin:$(brew --prefix)/opt/grep/libexec/gnubin:${PATH}"

See also brew info gettext for details on how to make that permanent in your shell.

In the same vein, if that's not already the case, you probably also want to make sure Homebrew's stuff takes precedence:

export PATH="/usr/local/bin:/usr/local/sbin:${PATH/:\/usr\/local\/bin/}"

Note: With current XCode versions, you will need to set a minimum deployment version higher than 10.04. Otherwise, you'll hit various linking errors related to missing unwinding libraries/symbols. On Mojave, 10.09 has been known to behave with XCode 10, And 10.14 with XCode 11. When in doubt, go with your current macOS version.


Note: On Catalina (10.15), you will currently NOT want to deploy for 10.15, as XCode is currently broken in that configuration! (i.e., deploy for 10.14 instead).

Getting the source

git clone
cd koreader && ./kodev fetch-thirdparty

Building the emulator

Building and running the emulator

To build an emulator on your Linux or macOS machine:

./kodev build

To run KOReader on your development machine:

./kodev run

Note: On macOS and possibly other non-Linux hosts, you might want to pass --no-build to prevent re-running the buildsystem, as incremental builds may not behave properly.

You can specify the size and DPI of the emulator's screen using -w=X (width), -h=X (height), and -d=X (DPI).

There is also a convenience -s (simulate) flag with some presets like kobo-aura-one, kindle3, and hidpi. The latter is a fictional device with --screen_width=1500, --screen_height=2000 and --screen_dpi=600 to help ensure DPI scaling works correctly.

Sample usage:

./kodev run -s=kobo-aura-one

To use your own koreader-base repo instead of the default one change the KOR_BASE environment variable:

make KOR_BASE=../koreader-base

This will be handy if you are developing koreader-base and you want to test your modifications with the KOReader frontend. NOTE: this only supports relative path for now.

Building for other platforms

Once you have the emulator ready to rock you can build for other platforms too.


You may need to check out the circleci config file to setup up a proper testing environment.

Briefly, you need to install luarocks and then install busted and ansicolors with luarocks. The "eng" language data file for tesseract-ocr is also need to test OCR functionality. Finally, make sure that luajit in your system is at least of version 2.0.2.

To automatically set up a number of primarily luarocks-related environment variables:

./kodev activate

To run unit tests:

./kodev test base
./kodev test front

To run a specific unit test (for test development):

./kodev test front readerbookmark_spec.lua

To run Lua static analysis:

make static-check

NOTE: Extra dependencies for tests: luacheck from luarocks.


Please refer to l10n's README to grab the latest translations from the KOReader project on Weblate with this command:

make po

If your language is not listed on the Weblate project, please don't hesitate to send a language request here.

Variables in translation

Some strings contain variables that should remain unaltered in translation. These take the form of a % followed by a number from 1-99, although you'll seldom see more than about 5 in practice. Please don't put any spaces between the % and its number. %1 should always remain %1. For example:

The title of the book is %1 and its author is %2.

This might be displayed as:

The title of the book is The Republic and its author is Plato.

To aid localization the variables may be freely positioned:

De auteur van het boek is %2 en de titel is %1.

That would result in:

De auteur van het boek is Plato en de titel is The Republic.

Use ccache

Ccache can speed up recompilation by caching previous compilations and detecting when the same compilation is being repeated. In other words, it will decrease build time when the sources have been built before. Ccache support has been added to KOReader's build system. To install ccache:

  • in Ubuntu use:sudo apt-get install ccache
  • in Fedora use:sudo dnf install ccache
  • from source:
    • download the latest ccache source from
    • extract the source package in a directory
    • cd to that directory and use:./configure && make && sudo make install
  • to disable ccache, use export USE_NO_CCACHE=1 before make.
  • for more information about ccache, visit: