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Software Release Practice HOWTO Eric S. Raymond <esr@thyrsus.com> 1.2, 18 June 1999 This HOWTO describes good release practices for Linux open-source pro¡ jects. By following these practices, you will make it as easy as pos¡ sible for users to build your code and use it, and for other develop¡ ers 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 pro¡ ject. It will be revised periodically to reflect the evolution of good-practice standards. ______________________________________________________________________ Table of Contents 1. Introduction 1.1 Why this document? 1.2 New versions of this document 2. Good project- and archive- naming practice 2.1 Use GNU-style names with a stem and major.minor.patch numbering. 2.2 But respect local conventions where appropriate 2.3 Try hard to choose a name prefix that is unique and easy to type 3. Good development practice 3.1 Write either pure ANSI C or a portable scripting language 3.2 Follow good C portability practices 3.3 Use autoconf/automake/autoheader 3.4 Sanity-check your code before release 4. Good distribution-making practice 4.1 Make sure tarballs always unpack into a single new directory 4.2 Have a README 4.3 Respect and follow standard file naming practices 5. Good communication practice 5.1 Announce to c.o.l.a 5.2 Announce to a relevant topic newsgroup 5.3 Have a website 5.4 Host project mailing lists 5.5 Release to major archives 5.6 Provide RPMs ______________________________________________________________________ 1. Introduction 1.1. Why this document? 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. 1.2. New versions of this document This document will be posted monthly to the newsgroups comp.os.linux.answers . The document is archived on a number of Linux FTP sites, including metalab.unc.edu in pub/Linux/docs/HOWTO. You can also view the latest version of this HOWTO on the World Wide Web via the 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, esr@snark.thyrsus.com <mailto:esr@snark.thyrsus.com>. 2. Good project- and archive- naming practice 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. 2.1. Use GNU-style names with a stem and major.minor.patch numbering. 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 foobar-1.2.3.tar.gz The source archive foobar.lsm The LSM file (assuming you're submitting to Metalab). Please don't use these: foobar123.tar.gz This looks to many programs like an archive for a project called`foobar123' with no version number. foobar1.2.3.tar.gz This looks to many programs like an archive for a project called `foobar1' at version 2.3. foobar-v1.2.3.tar.gz Many programs think this goes with a project called `foobar-v1'. foo_bar-1.2.3.tar.gz The underscore is hard for people to speak, type, and remember FooBar-1.2.3.tar.gz Unless you like looking like a marketing weenie. This is also hard for people to speak, type, and remember. 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 after the version number. That is, please do this: foobar-1.2.3.src.tar.gz sources foobar-1.2.3.bin.tar.gz binaries, type not specified foobar-1.2.3.bin.ELF.tar.gz ELF binaries foobar-1.2.3.bin.ELF.static.tar.gz ELF binaries statically linked foobar-1.2.3.bin.SPARC.tar.gz SPARC binaries Please don't 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: 1. project prefix 2. dash 3. version number 4. dot 5. "src" or "bin" (optional) 6. dot or dash (dot preferred) 7. binary type and options (optional) 8. archiving and compression extensions 2.2. But respect local conventions where appropriate 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. Look for and respect the conventions of specialized communities and developers; for general use, follow the above guidelines. 2.3. Try hard to choose a name prefix that is unique and easy to type 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 index file of Metalab <http://metalab.unc.edu/pub/Linux>. 3. Good development practice 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 will try to build your code on non-Linux systems; portability minimizes the number of annoying perplexed email messages you will get. 3.1. Write either pure ANSI C or a portable scripting language 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 not 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. 3.2. Follow good C portability practices 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&R compilers are history. On the other hand, do not 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. 3.3. Use autoconf/automake/autoheader 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. 3.4. Sanity-check your code before release 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.) 4. Good distribution-making practice These guidelines describe how your distribution should look when someone downloads, retrieves and unpacks it. 4.1. Make sure tarballs always unpack into a single new directory 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. Never do this! 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 beneath 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 VERS=1.0 foobar-$(VERS).tar.gz: tar --name-prefix='foobar-$(VERS)/' -czf foobar-$(VERS).tar.gz $(SRC) If you have an older tar program, do something like this: foobar-$(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)) 4.2. Have a README 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: ╖ A brief description of the project. ╖ A pointer to the project website (if it has one) ╖ Notes on the developer's build environment and potential portability problems. ╖ A roadmap describing important files and subdirectories. ╖ Either build/installation instructions or a pointer to a file containing same (usually INSTALL). ╖ Either a maintainers/credits list or a pointer to a file containing same (usually CREDITS). ╖ Either recent project news or a pointer to a file containing same (usually NEWS). 4.3. Respect and follow standard file naming practices 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. README or READ.ME the roadmap file, to be read first INSTALL configuration, build, and installation instructions CREDITS list of project contributers NEWS recent project news HISTORY project history COPYING project license terms (GNU convention) LICENSE project license terms MANIFEST list of files in the distribution FAQ plain-text Frequently-Asked-Questions document for the project TAGS generated tag file for use by Emacs or vi Note the overall convention that filenames with all-caps names are human-readable metainformation about the package, rather than build components. 5. Good communication practice 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. 5.1. Announce to c.o.l.a Announce new releases to comp.os.linux.announce <news:comp.os.linux.announce>. Besides being widely read itself, this group is a major feeder for web-based what's-new sites like Freshmeat <http://www.freshmeat.net>. 5.2. Announce to a relevant topic newsgroup Find USENET topics group directly relevant to your application, and announce there as well. Post only where the function 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. 5.3. Have a website 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: ╖ The project charter (why it exists, who the audience is, etc). ╖ Download links for the project sources. ╖ Instructions on how to join the project mailing list(s). ╖ A FAQ (Frequently Asked Questions) list. ╖ HTMLized versions of the project documentation ╖ Links to related and/or competing projects. Some project sites even have URLs for anonymous access to the master source tree. 5.4. Host project mailing lists 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 5.5. Release to major archives For the last several years, the Metalab archive <http://www.metalab.unc.edu/pub/Linux/> has been the most important interchange location for Linux software. Other important locations include: ╖ the Python Software Activity <http://www.python.org> site (for software written in Python). ╖ the CPAN <http://language.perl.com/CPAN>, the Comprehensive Perl Archive Network, (for software written in Perl). 5.6. Provide RPMs 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 a Slackware). Accordingly, it's a good idea for your project site to provide installable RPMs as well as source tarballs.