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<title>Software Release Practice HOWTO
<author>Eric S. Raymond &lt;esr@thyrsus.com&gt;
<date>2.3, 1 June 2000

<abstract>
This HOWTO describes good release practices for Linux open-source projects.
By following these practices, you will make it as easy as possible for
users to build your code and use it, and for other developers to understand
your code and cooperate with you to improve it.

This document is a must-read for novice developers.  Experienced developers 
should review it when they are about to release a new project.  It will be
revised periodically to reflect the evolution of good-practice standards.
</abstract>

<toc>

<sect>Introduction
<p>
<sect1>Why this document?
<p>
There is a large body of good-practice traditions for open-source code that
helps other people port, use, and cooperate with developing it.  Some of these
conventions are traditional in the Unix world and predate Linux; others
have developed recently in response to particular new tools and technologies
such as the World Wide Web.

This document will help you learn good practice.  It is organized into
topic sections, each containing a series of checklist items.  Think of
these as a pre-flight checklist for your distribution.

<sect1>New versions of this document
<p>
This document will be posted monthly to the newsgroups
<tt>comp.os.linux.answers</tt> . The document is archived on a number
of Linux FTP sites, including <tt>metalab.unc.edu</tt> in 
<tt>pub/Linux/docs/HOWTO</tt>.

You can also view the latest version of this HOWTO on the World
Wide Web via the URL <url
url="http://metalab.unc.edu/LDP/HOWTO/Software-Release-Practice.html">.

Feel free to mail any questions or comments about this HOWTO to 
Eric S. Raymond, <url 
url="mailto:esr@snark.thyrsus.com" name="esr@snark.thyrsus.com">. 

<sect>Good project- and archive- naming practice
<p>
As the load on maintainers of archives like Metalab, the PSA site and CPAN
increases, there is an increasing trend for submissions to be processed
partly or wholly by programs (rather than entirely by a human).

This makes it more important for project and archive-file names to fit
regular patterns that computer programs can parse and understand.

<sect1>Use GNU-style names with a stem and major.minor.patch numbering.
<p>
It's helpful to everybody if your archive files all have GNU-like
names -- all-lower-case alphanumeric stem prefix, followed by a dash,
followed by a version number, extension, and other suffixes.

Let's suppose you have a project you call `foobar' at version 1,
release 2, level 3.  If it's got just one archive part (presumably the
sources), here's what its names should look

<descrip>
<tag>foobar-1.2.3.tar.gz</tag> The source archive

<tag>foobar.lsm</tag> The LSM file (assuming you're submitting to Metalab).

</descrip>

Please <em>don't</em> use these:

<descrip>
<tag>foobar123.tar.gz</tag>This looks to many programs like an archive
for a project called`foobar123' with no version number.

<tag>foobar1.2.3.tar.gz</tag>This looks to many programs like an archive
for a project called `foobar1' at version 2.3.

<tag>foobar-v1.2.3.tar.gz</tag> Many programs think this goes with a
project called `foobar-v1'.

<tag>foo_bar-1.2.3.tar.gz</tag> The underscore is hard for people to speak,
type, and remember

<tag>FooBar-1.2.3.tar.gz</tag> Unless you <em>like</em> looking like a
marketing weenie.  This is also hard for people to speak, type, and remember.
</descrip>

If you have to differentiate between source and binary archives, or
between different kinds of binary, or express some kind of build
option in the file name, please treat that as a file extension to go
<em>after</em> the version number. That is, please do this:

<descrip>
<tag>foobar-1.2.3.src.tar.gz            </tag> sources

<tag>foobar-1.2.3.bin.tar.gz            </tag> binaries, type not specified

<tag>foobar-1.2.3.bin.ELF.tar.gz        </tag> ELF binaries

<tag>foobar-1.2.3.bin.ELF.static.tar.gz </tag> ELF binaries statically linked 

<tag>foobar-1.2.3.bin.SPARC.tar.gz      </tag> SPARC binaries
</descrip>

Please <em>don't</em> use names like `foobar-ELF-1.2.3.tar.gz', because
programs have a hard time telling type infixes (like `-ELF') from the
stem.

A good general form of name has these parts in order:

<enum>
<item>project prefix
<item>dash
<item>version number
<item>dot
<item>"src" or "bin" (optional)
<item>dot or dash (dot preferred)
<item>binary type and options (optional)
<item>archiving and compression extensions
</enum>

<sect1>But respect local conventions where appropriate
<p>
Some projects and communities have well-defined conventions for names and
version numbers that aren't necessarily compatible with the above advice.
For instance, Apache modules are generally named like mod_foo, and have
both their own version number and the version of Apache with which they
work.  Likewise, Perl modules have version numbers that can be treated as
floating point numbers (e.g., you might see 1.303 rather than 1.3.3), and
the distributions are generally named Foo-Bar-1.303.tar.gz for version
1.303 of module Foo::Bar.</p>

<p>Look for and respect the conventions of specialized
communities and developers; for general use, follow the above
guidelines.</p>

<sect1>Try hard to choose a name prefix that is unique and easy to type
<p>
The stem prefix should be common to all a project's files, and it
should be easy to read, type, and remember.  So please don't use
underscores.  And don't capitalize or BiCapitalize without extremely
good reason -- it messes up the natural human-eyeball search order and
looks like some marketing weenie trying to be clever.

It confuses people when two different projects have the same stem name.
So try to check for collisions before your first release.  A good place
to check is the <url url="http://metalab.unc.edu/pub/Linux" name="index
file of Metalab">.

<sect>Good licensing and copyright practice: the theory
<p>
The license you choose defines the social contract you wish to set up
among your co-developers and users.  The copyright you put on the software
will function mainly as a legal assertion of your right to set license
terms on the software and derivative works of the software.

<sect1>Open source and copyrights
<p>
Anything that is not public domain has a copyright, possibly more than
one.  Under the Berne Convention (which has been U.S. law since 1978),
the copyright does not have to be explicit.  That is, the authors of a
work hold copyright even if there is no copyright notice.<P>

Who counts as an author can be very complicated, especially for software
that has been worked on by many hands.  This is why licenses are 
important.  By setting out the terms under which material can be used,
they grant rights to the users that protect them from arbitrary
actions by the copyright holders.<P>

In proprietary software, the license terms are designed to protect the
copyright.  They're a way of granting a few rights to users while
reserving as much legal territory is possible for the owner (the
copyright holder).  The copyright holder is very important, and the
license logic so restrictive that the exact technicalities of the
license terms are usually unimportant.

In open-source software, the situation is usually the exact opposite;
the copyright exists to protect the license.  The only rights the
copyright holder always keeps are to enforce the license.  Otherwise,
only a few rights are reserved and most choices pass to the user.  In
particular, the copyright holder cannot change the terms on a copy you
already have.  Therefore, in open-source software the copyright holder
is almost irrelevant -- but the license terms are very important.

Normally the copyright holder of a project is the current project leader or
sponsoring organization.  Transfer of the project to a new leader is often
signaled by changing the copyright holder.  However, this is not a hard and
fast rule; many open-source projects have multiple copyright holders, and
there is no instance on record of this leading to legal problems.

Some projects choose to assign copyright to the Free Software Foundation,
on the theory that it has an interest in defending open source and lawyers
available to do it.

<sect1>What qualifies as open source
<p>
For licensing purposes, we can distinguish several different kinds of
rights that a license may convey.  Rights to <em>copy and
redistribute</em>, rights to <em>use</em>, rights to <em>modify for
personal use</em>, and rights to <em>redistribute modified
copies</em>.  A license may restrict or attach conditions to any
of these rights.

The <url name="Open Source Initiative" url="http://www.opensource.org"> is
the result of a great deal of thought about what makes software ``open
source'' or (in older terminology) ``free''.  Its constraints on licensing
require that:

<enum>
<item>An unlimited right to copy be granted.
<item>An unlimited right to use be granted.
<item>An unlimited right to modify for personal use be granted.
</enum>

The guidelines prohibit restrictions on redistribution of modified
binaries; this meets the needs of software distributors, who need to be
able to ship working code without encumbrance.  It allows authors
to require that modified sources be redistributed as pristine
sources plus patches, thus establishing the author's intentions and an
``audit trail'' of any changes by others.

The OSD is the legal definition of the `OSI Certified Open Source'
certification mark, and as good a definition of ``free software'' as
anyone has ever come up with.  All of the standard licenses (MIT, BSD,
Artistic, and GPL/LGPL) meet it (though some, like GPL, have other
restrictions which you should understand before choosing it).

Note that licenses which allow noncommercial use only do <em>not</em>
qualify as open-source licenses, even if they are decorated with
``GPL'' or some other standard license.  They discriminate against
particular occupations, persons, and groups.  They make life too
complicated for CD-ROM distributors and others trying to spread
open-source software commercially.

<sect>Good licensing and copyright practice: the practice
<p>
Here's how to translate the theory above into practice:

<sect1>Make yourself or the FSF the copyright holder
<p>
In some cases, if you have a sponsoring organization behind you with
lawyers, you might wish to give copyright to that organization.

<sect1>Use a license conformant to the Open Source Definition
<p>
The Open Source Definition is the community gold standard for licenses.
The OSD is not a license itself; rather, it defines a minimum set of rights
that a license must guarantee in order to be considered an open-source
license.  The OSD, and supporting materials, may be found at the web site
of the <url name="Open Source Initiative" url="http://www.opensource.org">.

<sect1>Don't write your own license if you can possibly avoid it.
<p>
The widely-known OSD-conformant licenses have well-established interpretive
traditions.  Developers (and, to the extent they care, users) know what
they imply, and have a reasonable take on the risks and tradeoffs they
involve.  Therefore, use one of the standard licenses carried on the OSI
site if at all possible.

If you must write your own license, be sure to have it certified by OSI.  This
will avoid a lot of argument and overhead.  Unless you've been through it, 
you have no idea how nasty a licensing flamewar can get; people become
passionate because the licenses are regarded as almost-sacred covenants
touching the core values of the open-source community.

Furthermore, the presence of an established interpretive tradition may
prove important if your license is ever tested in court.  At time of 
writing (late 1999) there is no case law either supporting or invalidating
any open-source license.  However, it is a legal doctrine (at least in
the U.S., and probably in other common-law countries such as England
and the rest of the British Commonwealth) that courts are supposed to 
interpret licenses and contracts according to the expectations and
practices of the community in which they originated.

<sect>Good development practice
<p>
Most of these are concerned with ensuring portability, not only across
Linuxes but to other Unixes as well.  Being portable to other Unixes 
is not just a worthy form of professionalism and hackerly politeness, 
it's valuable insurance against future changes in Linux itself.

Finally, other people <em>will</em> try to build your code on non-Linux
systems; portability minimizes the number of annoying perplexed email
messages you will get.

<sect1>Write either pure ANSI C or a portable scripting language
<p>
For portability and stability, you should write either in ANSI C or a
scripting language that is guaranteed portable because it has just one
cross-platform implementation.

Scripting languages that qualify include Python, Perl, Tcl, and Emacs Lisp.
Plain old shell does <em>not</em> qualify; there are too many different
implementations with subtle idiosyncracies, and the shell environment
is subject to disruption by user customizations such as shell aliases.

Java holds promise as a portable language, but the Linux-available 
implementations are still scratchy and poorly integrated with Linux.
Java is still a bleeding-edge choice, though one likely to become more
popular as it matures.

<sect1>Follow good C portability practices
<p>
If you are writing C, do feel free to use the full ANSI features --
including function prototypes, which will help you spot cross-module
inconsistancies.  The old-style K&amp;R compilers are history.

On the other hand, do <em>not</em> assume that GCC-specific 
features such as the `-pipe' option or nested functions are available.
These will come around and bite you the second somebody ports to a
non-Linux, non-GCC system.

<sect1>Use autoconf/automake/autoheader
<p>
If you're writing C, use autoconf/automake/autoheader to handle portability
issues, do system-configuration probes, and tailor your makefiles.  People
building from sources today expect to be able to type "configure; make"
and get a clean build -- and rightly so.

<sect1>Sanity-check your code before release
<p>
If you're writing C, test-compile with -Wall and clean up the errors at
least once before each release.  This catches a surprising number of
errors.  For real thoroughness, compile with -pedantic as well.

If you're writing Perl, check your code with perl -c (and maybe -T, if
applicable).  Use perl -w and 'use strict' religiously.  (See the Perl
documentation for discussion.)

<sect1>Sanity-check your documentation and READMEs before release
<p>
Run a spell-checker on them.  If you look like you can't spell and
don't care, pleople will assume you code is sloppy and careless too.

<sect>Good distribution-making practice
<p>
These guidelines describe how your distribution should look when someone
downloads, retrieves and unpacks it.

<sect1>Make sure tarballs always unpack into a single new directory
<p>
The single most annoying mistake newbie developers make is to build
tarballs that unpack the files and directories in the distribution into
the current directory, potentially stepping on files already located there.
<em>Never do this!</em>

Instead, make sure your archive files all have a common directory part
named after the project, so they will unpack into a single top-level 
directory directly <em>beneath</em> the current one.

Here's a makefile trick that, assuming your distribution directory is
named `foobar' and SRC contains a list of your distribution files,
accomplishes this.  It requires GNU tar 1.13

<verb>
VERS=1.0
foobar-$(VERS).tar.gz:
	tar --name-prefix='foobar-$(VERS)/' -czf foobar-$(VERS).tar.gz $(SRC)
</verb>

If you have an older tar program, do something like this:

<verb>
foobar-$(VERS).tar.gz:
	@ls $(SRC) | sed s:^:foobar-$(VERS)/: >MANIFEST
	@(cd ..; ln -s foobar foobar-$(VERS))
	(cd ..; tar -czvf foobar/foobar-$(VERS).tar.gz `cat foobar/MANIFEST`)
	@(cd ..; rm foobar-$(VERS))
</verb>

<sect1>Have a README
<p>
Have a file called README or READ.ME that is a roadmap of your source
distribution.  By ancient convention, this is the first file intrepid
explorers will read after unpacking the source.

Good things to have in the README include:

<itemize>
<item>A brief description of the project.
<item>A pointer to the project website (if it has one)
<item>Notes on the developer's build environment and potential portability
      problems.
<item>A roadmap describing important files and subdirectories. 
<item>Either build/installation instructions or a pointer to a file
      containing same (usually INSTALL).
<item>Either a maintainers/credits list or a pointer to a file containing
      same (usually CREDITS). 
<item>Either recent project news or a pointer to a file containing same
      (usually NEWS). 
</itemize>

<sect1>Respect and follow standard file naming practices
<p>
Before even looking at the README, your intrepid explorer will have scanned
the filenames in the top-level directory of your unpacked distribution.
Those names can themselves convey information.  By adhering to certain
standard naming practices, you can give the explorer valuable clues
about what to look in next.

Here are some standard top-level file names and what they mean.  Not
every distribution needs all of these.

<descrip>
<tag>README or READ.ME</tag> the roadmap file, to be read first

<tag>INSTALL</tag> configuration, build, and installation instructions

<tag>CREDITS</tag> list of project contributers

<tag>NEWS</tag> recent project news

<tag>HISTORY</tag> project history

<tag>COPYING</tag> project license terms (GNU convention)

<tag>LICENSE</tag> project license terms

<tag>MANIFEST</tag> list of files in the distribution

<tag>FAQ</tag> plain-text Frequently-Asked-Questions document for the project 

<tag>TAGS</tag> generated tag file for use by Emacs or vi
</descrip>

Note the overall convention that filenames with all-caps names are
human-readable metainformation about the package, rather than build
components.

Having a FAQ can save you a lot of grief.  When a question about the
project comes up often, put it in the FAQ; then direct users to read the
FAQ before sending questions or bug reports.  A well-nurtured FAQ can
decrease the support burden on the project maintainers by an order of
magnitude or more.

Having a HISTORY or NEWS file with timestamps in it for each release
is valuable.  Among other things, it may help establish prior art if
you are ever hit with a patent-infringement lawsuit (this hasn't
happened to anyone yet, but best to be prepared).

<sect1>Design for Upgradability
<p>
Your software will change over time as you put out new releases.  Some
of these changes will not be backward-compatible.  Accordingly, you
should give serious thought to designing your installation layouts so
that multiple installed versions of your code can coexist on the same
system.  This is especially important for libraries -- you can't 
count on all your client programs to upgrade in lockstep with your
API changes.

The Emacs, Python, and Qt projects have a good convention for handling
this; version-numbered directories.  Here's how an installed Qt
library hierarchy looks (&dollar;{ver} is the version number):

<verb>
/usr/lib/qt
/usr/lib/qt-${ver}
/usr/lib/qt-${ver}/bin          # Where you find moc
/usr/lib/qt-${ver}/lib          # Where you find .so
/usr/lib/qt-${ver}/include      # Where you find header files
</verb>

With this organization, you can have multiple versions coexisting.
Client programs have to specify the library version they want, but
that's a small price to pay for not having the interfaces break on them.

<sect1>Provide RPMs
<p>
The de-facto standard format for installable binary packages is that used
by the Red Hat Package manager, RPM.  It's featured in the most popular
Linux distribution, and supported by effectively all other Linux
distributions (except Debian and Slackware; and Debian can install from
RPMs).

Accordingly, it's a good idea for your project site to provide installable 
RPMs as well as source tarballs.

It's also a good idea for you to include in your source tarball the RPM
spec file, with a production that makes RPMs from it in your Makefile.
The spec file should have the extension `.spec'; that's how the rpm -t
option finds it in a tarball.

For extra style points, generate your spec file with a shellscript that
automatically plugs in the correct version number by analyzing the Makefile
or a version.h.

<sect>Good communication practice
<p>
Your software won't do the world much good if nobody but you knows it
exists.  Also, developing a visible presence for the project on the
Internet will assist you in recruiting users and co-developers.  Here
are the standard ways to do that.

<sect1>Announce to c.o.l.a and Freshmeat
<p>
Announce new releases to <url url="news:comp.os.linux.announce" 
name="comp.os.linux.announce">.  Besides being widely read itself,
this group is a major feeder for web-based what's-new sites like
<url url="http://www.freshmeat.net" name="Freshmeat">.

<sect1>Announce to a relevant topic newsgroup
<p>
Find USENET topics group directly relevant to your application, 
and announce there as well.  Post only where the <em>function</em> of the
code is relevant, and exercise restraint.

If (for example) you are releasing a program written in Perl that queries
IMAP servers, you should certainly post to comp.mail.imap.  But you
should probably not post to comp.lang.perl unless the program is also
an instructive example of cutting-edge Perl techniques.

Your announcement should include the URL of a project website.

<sect1>Have a website
<p>
If you intend try to build any substantial user or developer community
around your project, it should have a website.  Standard things to have
on the website include:
<itemize>
<item>The project charter (why it exists, who the audience is, etc).
<item>Download links for the project sources.
<item>Instructions on how to join the project mailing list(s).
<item>A FAQ (Frequently Asked Questions) list.
<item>HTMLized versions of the project documentation
<item>Links to related and/or competing projects.
</itemize>

Some project sites even have URLs for anonymous access to the master
source tree.

<sect1>Host project mailing lists
<p>
It's standard practice to have a private development list through which project
collaborators can communicate and exchange patches.  You may also
want to have an announcements list for people who want to be kept informed
of the project's process

<sect1>Release to major archives
<p>
For the last several years, the <url
url="http://www.metalab.unc.edu/pub/Linux/" name="Metalab archive"> has
been the most important interchange location for Linux software.

Other important locations include:

<itemize>
<item>the <url url="http://www.python.org" name="Python Software Activity">
site (for software written in Python).
<item>the <url url="http://language.perl.com/CPAN" name="CPAN">, the
Comprehensive Perl Archive Network, (for software written in Perl).
</itemize>

<sect>Good project-management practice
<p>
Managing a project well when all the participants are volunteers presents
some unique challenges.  This is too large a topic to cover in a HOWTO.
Fortunately, there are some useful white papers available that will help you
understand the major issues.

For discussion of basic development organization and the 
release-early-release-often `bazaar mode', see <url name="The Cathedral and
the Bazaar" url="http://www.tuxedo.org/~esr/writings/cathedral-bazaar/">.

For discussion of motivational psychology, community customs, and conflict
resolution, see
<url name="Homesteading the Noosphere"
url="http://www.tuxedo.org/~esr/writings/homesteading/">.

For discussion of economics and appropriate business models, see 
<url name="The Magic Cauldron"
url="http://www.tuxedo.org/~esr/writings/magic-cauldron/">.

These papers are not the last word on open-source development.  But they
were the first serious analyses to be written, and have yet to be
superseded.

</article>

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