ladybird/Ports
Daniel Bertalan 84c6d6649e Toolchain: Fix building the aarch64 toolchain
The `aarch64/t-aarch64` makefile fragment needs to be included for the
aarch64-specific parts of GCC to be built. Before 738e52da5, this was
done implicitly, but now it is not. This caused the following error when
building the toolchain: "aarch64-builtins.o: No such file or directory".
2022-01-04 17:40:09 +00:00
..
angband Ports: Enable SDL support in Angband 2021-11-01 11:34:25 +01:00
Another-World Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
bash Ports: Remove obsolete bash locale patch 2021-10-23 23:31:43 -07:00
bass Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
bc Ports: Enable history handling in bc 2021-10-25 21:42:26 +02:00
binutils Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
bison Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
brogue Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
byacc Ports/byacc: Remove obsolete getopt.h patch 2021-12-24 17:02:40 +03:30
bzip2 Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
c-ray Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
carl Ports: Update checksums to use the SHA256 algorithm 2021-04-25 13:30:18 +02:00
chester Ports/chester: Enable -Werror 2021-12-24 17:02:40 +03:30
cmake Ports: Upgrade CMake to 3.22.1 2021-12-24 17:01:10 +03:30
cmatrix Ports/cmatrix: Fix hash and update version 2021-11-06 00:42:02 -07:00
composer Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
curl Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
dash Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
dialog Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
diffutils Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
dmidecode Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
doom Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
dos2unix dos2unix: Swap to official signature validation 2021-12-09 09:48:43 +01:00
dosbox-staging Ports: Remove wchar patch from dosbox-staging 2021-12-21 20:35:52 -08:00
drascula Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
dreamweb Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
dropbear Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
dungeonrush Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
ed Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
emu2 Ports/emu2: Remove obsolete scandir patch 2021-12-24 17:02:40 +03:30
epsilon Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
ffmpeg Ports: Fix typo in ffmpeg dependencies 2021-11-01 10:45:15 +01:00
figlet Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
fio Ports: Add fio port 2021-12-22 13:28:13 -08:00
flatbuffers Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
flex Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
fontconfig Ports: Add Fontconfig port 2021-10-28 11:25:56 +02:00
fotaq Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
freeciv Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
freedink Ports: Add FreeDink port 2021-10-31 11:52:27 +01:00
freetype Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
frotz Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
gawk Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
gcc Toolchain: Fix building the aarch64 toolchain 2022-01-04 17:40:09 +00:00
gdb Ports/gdb: Add basic ptrace based native target for SerenityOS/i386 2021-12-29 03:17:41 -08:00
genemu Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
gettext Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
git Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
glib Ports: Add a dependency on pcre to glib 2021-11-06 01:16:14 -07:00
glm Ports: Add OpenGL Mathematics (GLM) port 2021-10-31 11:52:27 +01:00
glu Ports: Add Mesa GLU 2021-12-27 11:58:43 +01:00
gmp Ports: byacc+gmp+m4: Split auth_opts strings into array elements 2021-10-25 00:06:43 -07:00
gnucobol Ports: gnucobol: Build with ncurses and without NLS 2021-11-01 10:44:57 +01:00
gnupg Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
gnuplot Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
gperf Ports: Add GNU gperf port 2021-10-24 22:34:02 -07:00
grep Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
griffon Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
gsl Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
harfbuzz Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
hatari Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
imgcat Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
indent Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
jot Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
jq Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
klong Ports: Update checksums to use the SHA256 algorithm 2021-04-25 13:30:18 +02:00
less Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
libarchive Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
libassuan Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
libatomic_ops Ports: Add libatomic_ops 2021-08-21 13:16:51 +01:00
libexpat Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
libffi Ports: Bump libffi from version 3.3 to 3.4.2 2021-07-19 10:45:47 +02:00
libgcrypt Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
libgpg-error Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
libiconv Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
libicu Ports/libicu: Remove obsolete <cmath> header patch 2021-12-24 17:02:40 +03:30
libjpeg Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
libksba Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
libmodplug Ports: Fix issues with the libmodplug and SDL_sound ports 2021-10-10 19:11:02 -07:00
libogg Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
libopenal Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
libphysfs Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
libpng Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
libpuffy Ports: Fix building libpuffy 2021-05-01 22:52:15 +02:00
libsixel Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
libsodium Ports: Use immutable tarballs for libsodium 2021-11-03 11:10:38 +01:00
libssh2 Ports: Add libssh2 port 2021-12-20 10:43:47 -08:00
libtheora Ports/libtheora: Change download link to mirror with TLS1.2 support 2021-11-04 17:14:33 +01:00
libtiff Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
libtool Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
libuuid Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
libuv Ports/libuv: Fix build failure due to missing statfs() function 2021-12-27 02:02:03 -08:00
libvorbis Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
libxml2 Ports/libxml2: Remove obsolete ESHUTDOWN errno patch 2021-12-24 17:02:40 +03:30
libzip Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
links Ports: Updated links port to version 2.25 2021-12-16 22:45:05 +01:00
llvm Ports: Remove build-crt patch from llvm 2022-01-03 11:08:45 +00:00
lua Ports: Make lua buildable on x86_64 2021-12-28 00:24:32 +01:00
lure Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
m4 Ports/m4: Remove obsolete wint_t patch 2021-12-24 17:02:40 +03:30
make Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
mandoc Ports/mandoc: Remove obsolete patches 2021-12-24 17:02:40 +03:30
mawk Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
mbedtls Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
milkytracker Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
mpc Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
mpfr Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
mrsh Ports/mrsh: Remove obsolete PIPE_BUF patch 2021-12-24 17:02:40 +03:30
mruby Ports: Add port for mruby 2021-08-25 02:22:01 +02:00
mysthous Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
nano Ports: Fix nano authentication options splitting 2021-10-11 00:37:02 +01:00
nasm Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
ncdu Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
ncurses Ports/ncurses: Check for proper tic version during install 2021-12-20 10:45:52 -08:00
neofetch Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
nesalizer Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
nethack Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
ninja Ports: Remove obsolete patches for ninja 2021-07-04 00:35:35 +02:00
nippon Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
npth Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
ntbtls Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
nyancat Ports: Use "launcher_run_in_terminal=true" instead of "Terminal -e ..." 2021-07-20 00:58:26 +01:00
oksh Ports: Remove obsolete /dev/tty patches 2021-12-24 17:02:40 +03:30
openssh Ports: Remove wchar parts from openssh patches 2021-12-21 20:35:52 -08:00
openssl Ports: Compile OpenSSL with threads and as a shared library 2021-10-05 15:35:48 +01:00
openttd Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
openttd-opengfx Ports: Add openttd 2021-04-23 20:15:49 +02:00
openttd-opensfx Ports: Add openttd 2021-04-23 20:15:49 +02:00
opentyrian Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
opentyrian-data Ports: Add opentyrian and opentyrian-data 2021-05-31 19:01:49 +01:00
p7zip Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
patch Ports: Use GNU patch instead of the OpenBSD version 2021-11-10 14:48:39 +01:00
pcre Ports: Update pcre to 8.45 2021-11-06 12:40:19 +02:00
pcre2 Ports: Update pcre2 to 10.39 2021-11-06 00:32:36 -07:00
pfetch Ports: Add pfetch utility 2022-01-01 17:35:17 +00:00
php Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
pkgconf Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
printf Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
pt2-clone Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
pv Ports: Add initial Pipe Viewer (pv) 1.6.20 port 2021-11-14 16:18:45 +00:00
python3 Ports: Remove obsolete siginfo_t::si_error Python3 patch 2021-12-22 22:53:56 +02:00
quake Ports: quake: Do no set PATH environment variable in package.sh 2021-11-02 23:04:22 +01:00
quake2 Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
r0 Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
radare2 Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
readline Ports: Use sha256 sig check for readline 2021-07-29 15:58:38 +02:00
rsync Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
ruby Ports: Use ruby irb legacy mode 2021-10-15 21:56:06 -07:00
sam Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
scummvm Ports: Remove ScummVM's SVG patch 2021-11-18 21:10:30 +01:00
SDL2 Ports: Fix dependencies for SDL2 2021-10-16 15:36:04 -07:00
SDL2_gfx Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
SDL2_image Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
SDL2_mixer Ports: Compile SDL2_mixer with libmodplug support 2021-12-27 11:58:43 +01:00
SDL2_net Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
SDL2_ttf Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
SDL2-GNUBoy Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
SDL_sound Ports: Fix issues with the libmodplug and SDL_sound ports 2021-10-10 19:11:02 -07:00
SDLPoP Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
sed Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
sfinx Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
sl Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
soltys Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
sqlite Ports: Build an .so file for SQLite 2021-06-09 20:04:25 +02:00
stpuzzles Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
stress-ng Ports: Update stress-ng port to 0.13.09 2021-12-28 11:00:51 +01:00
Super-Mario Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
tcl Ports: Fix path for the tcl port's patch file 2021-04-27 17:59:52 +02:00
termcap Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
tinycc Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
tinyscheme Ports: Update checksums to use the SHA256 algorithm 2021-04-25 13:30:18 +02:00
tr Ports/tr: Remove obsolete getopt.h patch 2021-12-24 17:02:40 +03:30
tuxracer Ports: Implement SDL_QUIT event in Tux Racer 2021-12-30 14:24:29 +01:00
vim Ports/vim: Add symlink 'vi' pointing to target 'vim' 2021-10-31 21:09:49 +01:00
vitetris Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
vlang Ports: Bump vlang version to weekly.2021.31 2021-08-14 20:28:55 +02:00
vttest Ports: Update checksums to use the SHA256 algorithm 2021-04-25 13:30:18 +02:00
wget Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
xz Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
yasm Ports: Make array-like settings actual arrays 2021-10-05 02:13:08 +02:00
zlib Ports: Fix building zlib with Clang 2021-11-14 11:38:40 +00:00
zsh Ports: Add ZSH port 2021-06-09 19:41:23 +01:00
zstd Ports: Patch Makefile to use normal soname flags on Mac 2021-11-03 11:22:50 +01:00
.gitignore Ports: Build most python3 extension modules statically 2021-02-02 16:53:06 +01:00
.hosted_defs.sh Ports: Make it possible to build (some) ports with Clang 2021-10-17 17:09:58 +01:00
.port_include.sh Ports: Register all dependencies of ports 2021-10-21 14:48:21 +01:00
AvailablePorts.md Ports: Add pfetch utility 2022-01-01 17:35:17 +00:00
build_all.sh Ports: Don't add ports to the "built" list unless successful 2021-11-06 11:54:00 +01:00
build_installed.sh Ports: Replace hardcoded Build/ paths with SERENITY_BUILD_DIR 2021-03-11 21:01:29 +01:00
README.md Ports: Add overridable pre_fetch method in .port_include.sh 2021-07-22 22:30:55 +02:00

Ports for SerenityOS

What's this?

Serenity has software patched to run on it. These shell scripts will allow you to build that sort of software, easily. Note that you must have already built Serenity, and be in a Serenity build environment.

Available ports

A list of all available ports can be found here.

Using ports scripts

Each port has a script called package.sh which defines a name and version, its dependencies, the required files that will be downloaded as well as configuration/compilation options, and some other things (see Writing ports scripts for details).

  • To install a certain port, cd into its directory and run ./package.sh
  • To install all available ports, run the build_all.sh script in this directory. Pass clean as first argument to remove old build files beforehand.
  • To reinstall all currently installed ports, run the build_installed.sh script in this directory. This is sometimes required when LibC changes, for example. Pass clean as first argument to remove old build files beforehand.

Installed ports are being tracked in Build/i686/Root/usr/Ports/packages.db (a simple text file). You can delete this file at any time, in fact it must be edited or removed when clearing the build directory as port dependencies may not be installed again otherwise.

Not giving an option is equivalent to installdepends, fetch, patch, configure, build and install, in that order. This is recommended for a regular install.

Options

The following options are available:

fetch

By default, download, verify, and extract the port's files.

patch

Apply the port's patches (patches/*.patch). A file .foo_applied is created in workdir upon success to ensure a certain patch is only applied once.

configure

By default, run the port's configscript (usually configure) with configopts.

build

By default, run make with the port's makeopts.

install

By default, run make install with the port's installopts.

shell

Open a shell in the $workdir with the build environment set.

installdepends

Install all ports from the port's depends list.

clean

By default, remove all .out files from the port's workdir.

clean_dist

By default, remove everything that's been downloaded from the port's files list.

clean_all

By default, clean and clean_dist combined.

uninstall

Remove the port's files from the Serenity build directory, if it has a plist file.

--auto

Same as no option, but mark the port as having been installed automatically. This is used for dependencies.

Writing ports scripts

The package.sh file is a simple Bash script that's required for each port. Patches and other files are optional. The most basic version of such a port script simply defines some well-known variables and looks like this:

#!/usr/bin/env -S bash ../.port_include.sh

port="foo"
version="1.2.3"
useconfigure="true"
files="https://example.com/foo-${version}.tar.gz foo-${version}.tar.gz"
depends="bar baz"

The script in the shebang, .port_include.sh, is where all the magic happens.

Variables

The following variables have special functionality:

auth_import_key

PGP key to import (from keyserver.ubuntu.com) when auth_type is sig.

auth_opts

Options passed to gpg --verify when auth_type is sig.

Usually used like this:

auth_opts="foo-${version}.tar.xz.asc foo-${version}.tar.xz"

auth_type

The type of file validation to use, can be one of:

  • md5: Use MD5 hashes defined in files
  • sha256: Use SHA256 hashes defined in files
  • sha1: Use SHA1 hashes defined in files
  • sig: Use PGP signatures (see auth_opts)

Defaults to md5, most ports use sig though as .asc files are widely available.

configopts

Options passed to the port's configscript in the default configure function.

--host=i686-pc-serenity is always passed, override the configure function if that's undesirable.

configscript

Name of the script that will be run in the default configure function when useconfigure is true.

Defaults to configure.

depends

A space-separated list of other SerenityOS ports the port depends on and which will be installed during the installdepends step.

files

A list of external files required by the port, one per line. The format of each line is as follows:

URL NAME HASH

Where URL is the URL from where the file will be downloaded (using curl), NAME is the output name of the downloaded file, and HASH is an optional MD5, SHA1, or SHA256 hash that will be used for verification when auth_type is set to either of those hash functions.

For example:

files="https://example.com/foo-${version}.tar.xz foo-${version}.tar.xz
https://example.com/foo-${version}.tar.xz.asc foo-${version}.tar.xz.asc"

If a file is a compressed tar archive, a gzip compressed file or a zip compressed file, it will be extracted.

If a file is an .asc file (PGP signature) it will be imported into gpg's keyring and can later be used for verification using auth_opts.

icon_file

The file to use for the port launcher icon. The icon file is assumed to have a 16x16 as well as a 32x32 layer.

installopts

Options passed to make install in the default install function.

DESTDIR="${SERENITY_INSTALL_ROOT}" ("${SERENITY_SOURCE_DIR}/Build/${SERENITY_ARCH}/Root") is always passed, override the install function if that's undesirable.

makeopts

Options passed to make in the default build function.

Defaults to -j$(nproc).

patchlevel

The value for patch's -p / --strip option, see man patch for details.

Defaults to 1.

port

The "package name" of the port, usually the same as the directory this script is placed in.

prefix

The location of the ports directory, only used for the package.db file for now. Don't override this in ports contributed to Serenity.

Defaults to $SERENITY_SOURCE_DIR/Ports.

useconfigure

The configure step will run pre_configure and configure when this is set to true, and simply skip them otherwise.

Defaults to false.

version

The version of the port. Written to package.db, and usually used with variable interpolation in files where the version is part of the filename.

workdir

The working directory used for executing other commands via run as well as cleanup. Usually the directory name of the upacked source archive.

Defaults to $port-$version.

Functions

The various steps of the port installation process are split into individual Bash functions, some of which can be overridden to provide custom behaviour, like this:

build() {
    run mybuildtool --foo --bar
}

The following can be overridden, the names should be self-explanatory as they mostly match the available options:

  • pre_fetch
  • post_fetch
  • pre_configure
  • configure.
  • build
  • install
  • post_install
  • clean
  • clean_dist
  • clean_all

A few (non-overridable) util functions are available as well:

run

Log the command and run it in the port's workdir.

run_nocd

Log the command and run it in the current working directory (i.e. Ports/$port).

run_replace_in_file

Replace something in a file (using a Perl regular expression), like this:

run_replace_in_file "s/define FOO 1/undef FOO/" config.h

How do I contribute?

You can either:

  • Add new ports - just get the software to build and add the necessary patches and package.sh script
  • Update an existing port: bumping its version, getting functionality to work that wasn't available so far etc. Make sure to update the patches accordingly.

Some videos of Andreas adding new ports can be found on YouTube, they might help you understand how this usually works: