erln8, reo, and reo3 all share the same command line parameters.

Environment

Showing the current version in a given directory

erln8 --show

This command searches up the directory tree from the current working directory to find an erln8.config file containing a version of Erlang/Rebar/Rebar3 to use. If the root directory is reached without finding an erln8.config file, the erln8/reo/reo3 system_default is used. If a system_default isn't specified, the command will fail.

Listing installed versions

erln8 --list

Setting and getting the system default

If erln8 can't find an erln8.config file in the current and all parent directories (stopping at /), the system default will be used.

erln8 --set-default OTP-18.0

erln8 --get-default

Building

Listing buildable versions

This will list buildable tags across all configured repos. Note that you don't need to build from a tag, you can use a git SHA etc.

erln8 --buildable

Building the latest version

If you're confident that the local OTP/rebar/rebar3 repos are up-to-date, simply issue:

erln8 --build-latest

It's always a good idea to run a fetch first though:

erln8 --fetch default # fetches the default OTP repo
erln8 --build-latest

Building multiple versions at once

You can build multiple versions with one command:

erln8 --build OTP_R16B03-1 --build OTP-17.0 --build OTP-18.0

Advanced Builds

Building from an alternate repo:

erln8 --build origin/basho-otp-18 --repo basho --id basho18

Note: the origin/ prefix may be required when working with repos other than default.

Repos + Multiple Repositories

The default erln8 repo is the canonical OTP repository https://github.com/erlang/otp.git. You can, however, build from multiple repos.

Display a list of configured repos

erln8 --repos
default -> https://github.com/erlang/otp.git
basho -> https://github.com/basho/otp.git

Adding and removing remotes

You can add additional repos to build Erlang from via --remote add:

erln8 --remote add basho https://github.com/basho/otp.git
erln8 --clone basho

You must clone each repo after it's added.

Cloning remotes

Fetching from remotes

To pull down new git objects from the default OTP repository:

erln8 --fetch default
# pull down objects from a repo named "basho"
erln8 --fetch basho

Configs

You can specify an Erlang build config via the --config parameter, or via the [Erln8]/default_config value in ~/.erln8.d/config.

Environment variables

To provide environment variables to a build, create a custom config and an config environment. A config environment is the name of the config followed by _env in the [Config] section of ~/.erln8.d/config.

For example, the config osx_gcc has a osx_gcc_env config environment that will be passed to the build when using erln8 --build foo --config osx_gcc:

osx_gcc=--disable-hipe --enable-smp-support --enable-threads --enable-kernel-poll --enable-darwin-64bit
osx_gcc_env=CC=gcc-4.2 CPPFLAGS='-DNDEBUG' MAKEFLAGS='-j 3'k

erln8 config parameters

The erln8 configuration file ~/.erln8.d/config contains several parameters that you can tweak.

Erln8

The [Erln8] section allows you to specify the following parameters:

Parameter	Description
default_config	The default configuration to use for all builds, unless overriden by --config.
system_default	The version to use as a system-wide default. See --get-default and --set-default.
log_level	valid values are error or info
color	unimplemented in erln8 v2

Repos

The [Repos] section allows you to manually configure OTP repos to build from.

Parameter	Description
default	The canonical Erlang OTP repo: https://github.com/erlang/otp.git. This repo must exist for erln8 to work.
<repo_name>	A custom repo with the name repo_name at url repo_url. \<repo_name>=\<repo_url>

Erlangs

The [Erlangs] section maintains a list of Erlang versions that have been built by erln8.

Parameter	Description
none	No Erlang configured at this location. Probably not useful to you!

Configs

The [Configs] section maintains a list build configurations for Erlang.

Parameter	Description
default	Empty build configuration.
<config_name>	Custom build flags to pass to the Erlang build
<config_name>_env	Custom build environment variables to pass to the Erlang build

Regenerating erln8 links

If the links in ~/.erln8.d/bin become invalid, or the binary moves, you can recreate them with:

erln8 --setup-bins

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© 2015 Dave Parfitt