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A Beginner's Guide to Compiling Source Code

Issue 32

From Issue #32
December 1996

Dec 01, 1996  By Larry Ayers
 in
If you've been hesitant to compile Linux source code, hesitate no more—this article gives complete instructions for your first foray.
A Few Hints

In several instances I've failed miserably with a source distribution, then weeks or months later downloaded a later version and had it compile cleanly. Perhaps I updated a library the Makefile was looking for, or perhaps the author made a change in the source which fortuitously caused the program to be compatible with my system. In other words, it's worthwhile to try again later when you initially have a problem.

Another situation I've found myself in: after several edits of the Makefile and perhaps a few header files I'm getting more and more compiler errors. Nothing seems to work and I can't seem to make any headway. This is an ideal time to delete the entire directory tree and reinstall it from the archive file. Sometimes a completely fresh start helps.

One compiler flag to watch out for in the Makefile is -g (as in gcc -g). The GNU programs often have this flag, which instructs the compiler to add bulky debugging code to the executable. This is needed if you plan to use a debugger on the program. I don't even have a debugger installed, so I routinely remove that flag. The strip utility will remove this debugging code, often reducing an executable to half its original size.

Virtual consoles are tailor-made for compiling. Once you've set a lengthy compilation in motion, just switch to another console and start something else. I like to shut down X-Windows while compiling, as gcc uses all of the processor cycles it can get. The more resources that are available, the faster your program will compile.

Conclusion

So what do you gain from learning to compile programs?

  • The range of software available to you is considerably increased.

  • I believe there is an advantage to using an executable tuned to your system and configuration.

  • You have the opportunity to specify compiler flags, like >\#140>O2, to optimize the code. Sometimes there are compile-time options that can be set or unset in the Makefile.

  • Functions or subroutines in the program you know you will never need can be left out of the executable.

  • Source code is often the only form in which successive builds are available in beta-testing scenarios.

  • Often more complete documentation will be included with source code than with a binary distribution.

  • It is interesting to get glimpses into the way programs are put together. Often source files are heavily commented, because the programmer might want to explain sections of code to present or future collaborators in the project.

Larry Ayers (layers@vax2.rain.gen.mo.us) lives on a small farm in norther Missouri, where he is currently engaged in building a timber-frame house for his family. He operates a portable band-saw mill, does general woodworking, plays the fiddle and searches for rare prairie plants, as well as growing shiitake mushrooms. He is also struggling with configuring a Usenet news server for his local ISP.

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The article had nothing that

Anonymous's picture
Submitted by Anonymous (not verified) on Mon, 11/30/2009 - 03:45.

The article had nothing that would help anybody to compile anything. You are only explaining the technology. The title is very misleading.

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