Building Software Packages for Linux

Building Software Packages for Linux
Mendel Leo Cooper <mailto:[email protected]>
http://personal.riverusers.com/~thegrendel/
v1.3, 13 August 1997

This document is a guide to building "generic" UNIX software distribu�
tions under Linux.

1. Introduction

Many software packages for the various flavors of UNIX, including
Linux, are distributed as compressed archives of source files. The
same package may be "built" to run an various target machines, and
this saves the author of the software from having to produce multiple
distributions. A single distribution of a software package may thus
end up running, in various incarnations, on an Intel box, a DEC Alpha,
a RISC workstation, or even a mainframe. Unfortunately, this puts the
responsibility of actually "building" the software on the end user,
the de facto "system administrator", the fellow sitting at the
keyboard... you. Take heart, though, the process is not nearly as
terrifying or mysterious as it seems, and this guide will attempt to
demonstrate just that.

2. Getting Started

You have downloaded or otherwise retrieved a software package. Most
likely it is archived (tarred) and compressed (gzipped), in .tar.gz or
.tgz form. It must first be copied to a working directory. Then it is
necessary to untar and gunzip it. The appropriate command is tar xzvf
filename, where filename is the name of the software file, of course.
The de-archiving process will usually install the appropriate files in
subdirectories it will create. Note that if the package name has a .Z
suffix, it will require uncompress PACKAGENAME, then tar xvf
PACKAGENAME rather than the above procedure.

Sometimes the archived file must be untarred and installed from the
user's home directory, or perhaps in a certain other directory,
according to the package's config info. Should you get an error
message attempting to untar it, this may be the cause. Read the
package docs (especially the README and/or Install files, if present)
and edit the config files and/or Makefiles and Imake files, as
necessary, consistent with the installation instructions. Some
software packages permit automating this process by running make
install to emplace the binaries in the appropriate system areas.

You are now ready to proceed to the build stage of the process.

3. Using Make

The Makefile is the key to the build process. In its simplest form, a
Makefile is a script for compiling or building the "binaries", the
executable portions of a program. The Makefile can also provide a
means of updating a software package without having to recompile every
single source file in it, but that is a different story (or a
different article).

At some point, the Makefile launches cc or gcc. This is actually a
preprocessor, a C (or C++) compiler, and a linker, invoked in that
order. This process converts the source into the binaries, the actual
executables.

Only the simplest software uses a generic Makefile. More complex
installations require tailoring the Makefile according to the location
of libraries, include files, and resources on your particular machine.
This is especially the case when the build needs the X11 libraries to
install. Imake and xmkmf accomplish this task.

An Imakefile is, to quote the man page, a "template" Makefile. The
imake utility constructs a Makefile appropriate for your system from
the Imakefile. In almost all cases, however, you would run xmkmf, a
shell script that invokes imake, a front end for it. Check the README
or INSTALL file included in the software archive for specific
instructions. Read the imake and xmkmf man pages for a more detailed
analysis of the procedure..

Be aware that xmkmf and make may need to be invoked as root,
especially when doing a make install to move the binaries over to the
/usr/bin or /usr/local/bin directories. Using make as an ordinary
user without root privileges will likely result in write access denied
error messages because you lack write permission to system
directories. Check also that the binaries created have the proper
execute permissions for you and any other appropriate users.

Invoking xmkmf uses the imake file to build a new Makefile appropriate
for your system. It sets the variables and defines the library
locations for the compiler and linker. Sometimes, there will be no
imake file, instead there will be an INSTALL script that will
accomplish this purpose. The README file included with the
distribution will usually explain the install procedure.

Your general installation procedure will therefore be:

� Read the README file.

� Run xmkmf or the INSTALL script.

� If necessary, run make clean or make depend

� Run make.

� If necessary, run make install

4. Troubleshooting

If xmkmf and/or make succeeded without errors, you may proceed to the
``next section''. However, in "real life", few things work right the
first time. This is when your resourcefulness is put to the test.

4.1. Link Errors

� Suppose make fails with a Link error: -lX11: No such file or
directory, even after xmkmf has been invoked. This may mean that
the imake file was not set up properly. Check the first part of the
Makefile for lines such as:

LIB= -L/usr/X11/lib
INCLUDE= -I/usr/X11/include/X11
LIBS= -lX11 -lc -lm

The -L and -I switches tell the compiler and linker where to look for
the library and include files, respectively. In this example, the X11
libraries should be in the /usr/X11/lib directory, and the X11 include
files should be in the /usr/X11/include/X11 directory. If this is
incorrect for your machine, make the necessary changes to the Makefile
and try the make again.

� -----------------------------------------------------------------

� In a very few cases, running ldconfig as root may be the solution:

# /etc/ldconfig -n /lib will update the shared library symbolic
links. This should not be necessary under normal circumstances.

� -----------------------------------------------------------------

� Yet another thing to try if xmkmf fails is the following script:

make -DUseInstalled -I/usr/X386/lib/X11/config

� -----------------------------------------------------------------

� Sometimes the source needs the older release X11R5 libraries to
build. If you have the R5 libs in /usr/X11R6/lib (you were given
the option of having them when first installing Linux), then you
need only ensure that you have the links that the software needs to
build. The R5 libs are named libX11.so.3.1.0, libXaw.so.3.1.0, and
libXt.so.3.1.0. You generally need links, such as libX11.so.3 ->
libX11.so.3.1.0. Possibly the software will also need a link of the
form libX11.so -> libX11.so.3.1.0. Of course, to create a
"missing" link, use the command ln -s libX11.so.3.1.0 libX11.so, as
root.

4.2. Other Problems

� An installed Perl or shell script gives you a No such file or
directory error message. In this case, check the file permissions
to make sure the file is executable and check the file header to
ascertain whether the shell or program invoked by the script is in
the place specified. For example, the scrip may begin with:

#!/usr/local/bin/Perl

If Perl is in fact installed in your /usr/bin directory instead of the
/usr/local/bin one, then the script will not run. Edit and correct the
script file header in such a case.

� -----------------------------------------------------------------

� Some X11 software requires the Motif libraries to build. The
standard Linux distributions do not have the Motif libraries
installed, and at present Motif costs an extra $100-$200 (though
the freeware Lesstif may also work in many cases). If you need
Motif to build a certain package, but lack the Motif libraries, it
may be possible to obtain statically linked binaries. Static
linking incorporates the library routines in the binaries
themselves. This results in much larger binary files, but the code
will run even on systems lacking the libraries.

4.3. Where to go for more help

In my experience, about 25% of applications build "right out of the
box". Another 50% or so can be persuaded to build with an effort
ranging from trivial to herculean. That still means a significant
number of packages will not build no matter what. Even then, the Intel
ELF and/or a.out binaries for these might possibly be found at Sunsite
<ftp://sunsite.unc.edu>, the TSX-11 archive <ftp://tsx-11.mit.edu> or
other places. Perhaps the author of the software can supply the
binaries compiled for your particular flavor of machine.

Note that if you obtain precompiled binaries, you will need to check
for compatibility with your system:

� The binaries must run on your hardware (i.e., Intel x86).

� The binaries must be compatible with your kernel (i.e., a.out or
ELF).

If all else fails, you may find help in the appropriate newsgroups,
such as comp.os.linux.x or comp.os.linux.development. Once in a
while, though, you are just plain out of luck, but hey, it was fun
trying.

5. Final Steps

Read the software package documentation to determine whether certain
environmental variables need setting (in .bashrc or .cshrc) and if the
.Xdefaults and .Xresources files need customizing.

There may be an applications default file, usually named Xfoo.ad in
the original Xfoo distribution. If so, edit the Xfoo.ad file to
customize it for your machine, then rename (mv) it Xfoo and install it
in the /usr/lib/X11/app-defaults directory, as root. Failure to do
this may cause the software to misbehave or even refuse to run.

Most software packages come with one or more preformatted man pages.
As root, copy the Xfoo.man file to the appropriate /usr/man directory
(man1 - man9), and rename it accordingly. For example, if Xfoo.man
ends up in /usr/man/man4, it should be renamed Xfoo.4 (mv Xfoo.man
Xfoo.4).

Note that some or all of the above procedures may in certain cases be
handled automatically by a make install. If so, the README or INSTALL
doc file will specify this.

6. First Example: Xscrabble

Matt Chapman's Xscrabble seemed like a program that would be
interesting to have, since I happen to be an avid Scrabble[TM] player.
I downloaded it, uncompressed it, and built it following the
procedure in the README file:

xmkmf
make Makefiles
make includes
make

Of course it did not work...

______________________________________________________________________
gcc -o xscrab -O2 -O -L/usr/X11R6/lib
init.o xinit.o misc.o moves.o cmove.o main.o xutils.o mess.o popup.o
widgets.o display.o user.o CircPerc.o
-lXaw -lXmu -lXExExt -lXext -lX11 -lXt -lSM -lICE -lXExExt -lXext -lX11
-lXpm -L../Xc -lXc

BarGraf.o(.text+0xe7): undefined reference to `XtAddConverter'
BarGraf.o(.text+0x29a): undefined reference to `XSetClipMask'
BarGraf.o(.text+0x2ff): undefined reference to `XSetClipRectangles'
BarGraf.o(.text+0x375): undefined reference to `XDrawString'
BarGraf.o(.text+0x3e7): undefined reference to `XDrawLine'
etc.
etc.
etc...
______________________________________________________________________

I enquired about this in the comp.os.linux.x newsgroup, and someone
kindly pointed out to me that apparently the Xt, Xaw, Xmu, and X11
libs were not being found at the link stage. Hmmm...

There were two main Makefiles, and the one in the src directory caught
my interest. One line in the Makefile defined LOCAL_LIBS as:
LOCAL_LIBS = $(XAWLIB) $(XMULIB) $(XTOOLLIB) $(XLIB) Here were
references to the libs not being found by the linker.

Looking for the next reference to LOCAL_LIBS, I saw on line 495 of
that Makefile:

$(CCLINK) -o $@ $(LDOPTIONS) $(OBJS) $(LOCAL_LIBS) $(LDLIBS)
$(EXTRA_LOAD_FLAGS)

Now what were these LDLIBS?

LDLIBS = $(LDPOSTLIB) $(THREADS_LIBS) $(SYS_LIBRARIES)
$(EXTRA_LIBRARIES)

The SYS_LIBRARIES were:

SYS_LIBRARIES = -lXpm -L../Xc -lXc

Yes! Here were the missing libraries.

Possibly the linker needed to see the LDLIBS before the LOCAL_LIBS...
So, the first thing to try was to modify the Makefile by transposing
the $(LOCAL_LIBS) and $(LDLIBS) on line 495, so it would now read:

$(CCLINK) -o $@ $(LDOPTIONS) $(OBJS) $(LDLIBS) $(LOCAL_LIBS)
$(EXTRA_LOAD_FLAGS) ^^^^^^^^^^^^^^^^^^^^^^^

I tried running make again with the above change, and lo and behold,
it worked this time. Of course, Xscrabble still needed some fine
tuning and twiddling, such as renaming the dictionary and commenting
out some assert statements in one of the source files, but since then
it has been providing me with many hours of pleasure.

You may e-mail Matt Chapman <mailto:[email protected]>, and
download Xscrabble from his home page
<http://www.belgarath.demon.co.uk/programs/index.html>.

______________________________________________________________________
Scrabble is a registered trademark of the Milton Bradley Co., Inc.
______________________________________________________________________

7. Second Example: Xloadimage

The second example poses an easier problem. The xloadimage program
seemed a useful addition to my set of graphic tools. I copied the
xloadi41.gz file directly from the source directory on the CD included
with the excellent ``X User Tools'' book, by Mui and Quercia. As
expected, tar xzvf unarchives the files. Make, however, produces a
nasty-looking error and terminates.

______________________________________________________________________
gcc -c -O -fstrength-reduce -finline-functions -fforce-mem
-fforce-addr -DSYSV -I/usr/X11R6/include
-DSYSPATHFILE=\"/usr/lib/X11/Xloadimage\" mcidas.c

In file included from /usr/include/stdlib.h:32,
from image.h:23,
from xloadimage.h:15,
from mcidas.c:7:
/usr/lib/gcc-lib/i486-linux/2.6.3/include/stddef.h:215:
conflicting types for `wchar_t'
/usr/X11R6/include/X11/Xlib.h:74: previous declaration of
`wchar_t'
make[1]: *** [mcidas.o] Error 1
make[1]: Leaving directory
`/home/thegrendel/tst/xloadimage.4.1'
make: *** [default] Error 2
______________________________________________________________________

The error message contains the essential clue.

Looking at the file image.h, line 23...

______________________________________________________________________
#include <stdlib.h>
______________________________________________________________________

Aha, somewhere in the source for xloadimage, wchar_t has been rede�
fined from what was specified in the standard include file, stdlib.h.
Let us first try commenting out line 23 in image.h, as perhaps the
stdlib.h include is not, after all, necessary.

At this point, the build proceeds without any fatal errors. The
xloadimage program functions correctly now.

8. Final Words

To sum up, persistence makes all the difference (and a high
frustration threshold certainly helps). As in all endeavors, learning
from mistakes is critically important. Each misstep, every failure
contributes to the body of knowledge that will lead to mastery of the
art of building software.

9. References and Further Reading

BORLAND C++ TOOLS AND UTILITIES GUIDE, Borland International, 1992,
pp. 9-42.
[One of the manuals distributed with Borland C++, ver. 3.1. Gives
a fairly good intro to Make syntax and concepts, using Borland's limited
implementation thereof.]

DuBois, Paul: SOFTWARE PORTABILITY WITH IMAKE, O'Reilly and Associates,
1996, ISBN 1-56592-226-3.
[This is reputed to be the definitive Imake reference, though I did not
have it available when writing this article.]

Lehey, Greg: PORTING UNIX SOFTWARE, O'Reilly and Associates, 1995, ISBN
1-56592-126-7.

Mui, Linda and Valerie Quercia: X USER TOOLS, O'Reilly and Associates,
1994, ISBN 1-56592-019-8, pp. 734-760.

Oram, Andrew and Steve Talbott: MANAGING PROJECTS WITH MAKE, O'Reilly
and Associates, 1991, ISBN 0-937175-90-0.

Stallman, Richard M. and Roland McGrath: GNU MAKE, Free Software
Foundation, 1995, ISBN 1-882114-78-7.

Welsh, Matt and Lar Kaufman: RUNNING LINUX, O'Reilly and Associates,
1995, ISBN 1-56592-100-3, pp. 325-333, 377-379, 381.
[Still the best overall Linux reference, though lacking in depth
in some areas.]

And, of course, the man pages for make, imake, xmkmf, and ldconfig.