This file is created from the TeX-manual by throwing away some TeX-Macro-Calls.


                              Installing XGAP

Installing XGAP should be easy once you have installed GAP itself. We
assume here that you want to install XGAP in its standard location,
which is in the "pkg" subdirectory of the main GAP4 installation.


\Section{Overview}

You have to perform the following steps to install XGAP:

-- Get the sources
-- Unpack the sources with the <unzoo> utility
-- Use the <configure> script to adjust everything to your specific system
-- Compile the C part of XGAP
-- Edit a certain startup script and install it in an executable
   location in your system

\Section{What you need to install XGAP}

Being a graphical user interface to GAP, XGAP of course needs
graphics. At the moment this means that you need the X window system in the 
Version 11 Release 5 or newer. So you *cannot* use XGAP on a Macintosh
or a Microsoft Windows computer. On the other hand the type of Unix you use 
should not matter. Please contact Max Neunhoeffer (email:
`max.neunhoeffer@math.rwth-aachen.de') or post to the gap-trouble  
mailing list, if you encounter problems with certain system configurations.

Because XGAP contains a C-part you need a C compiler.


\Section{Getting and unpacking the sources}

You can download the sources from the same places as GAP. So the main
FTP servers are:

ftp://ftp-gap.dcs.st-and.ac.uk/pub/gap/gap4/
ftp://ftp.math.rwth-aachen.de/pub/gap4/
ftp://ftp.ccs.neu.edu/pub/mirrors/ftp-gap.dcs.st-and.ac.uk/pub/gap/gap4/
ftp://pell.anu.edu.au/pub/algebra/gap4/


You need only one file with the name "xgap4r00.zoo" which is in the
subdirectory for the share packages.  When you installed GAP you used the
utility <unzoo> to unpack the distribution. You will need this here
again. See the GAP-manual for instructions on how to get and compile this.
You now change your current directory to the `pkg' subdirectory of the 
location where you installed GAP (you typed an <unzoo>-command, then a new 
directory called "gap4" or something like that was created, this directory
contains the `pkg' subdirectory). The standard location would be:

# cd /usr/local/lib/gap4/pkg
(do not type the prompt character #)

Now you extract the sources for the XGAP share package:

# unzoo -x xgap4.zoo
xgap/README     -- extracted as text
xgap/Makefile.in        -- extracted as text
xgap/configure  -- extracted as text
xgap/configure.in       -- extracted as text
xgap/init.g     -- extracted as text
xgap/cnf/Makefile       -- extracted as text
xgap/cnf/Makegap.in     -- extracted as text
xgap/cnf/Makegap.top    -- extracted as text
xgap/cnf/config.hin     -- extracted as text
xgap/cnf/configure.in   -- extracted as text
xgap/cnf/configure.out  -- extracted as text
xgap/doc/answers.tex    -- extracted as text
xgap/doc/diffgap3.tex   -- extracted as text
/bin/mkdir: cannot make directory `xgap': File exists
...

Note that the warning is *not* serious.

The <unzoo> utility unpacks the files and stores them into the apropriate
subdirectories. XGAP resides completely in the following subdirectory
(assuming standard location):

/usr/local/lib/gap4/pkg/xgap


\Section{Configuring and Compiling the C part}

You have to change your current working directory to the "xgap"
subdirectory. You do this by

# cd xgap

if your current working directory is the one, where you used
<unzoo>. There you invoke the <configure> script by:

# ./configure
creating cache ./config.cache
checking for make... make
checking host system type... i686-unknown-linux2.0.34
checking target system type... i686-unknown-linux2.0.34
checking build system type... i686-unknown-linux2.0.34
checking for gcc... gcc
checking whether the C compiler (gcc  ) works... yes
checking whether the C compiler (gcc  ) is a cross-compiler... no
checking whether we are using GNU C... yes
...
updating cache ./config.cache
creating ./config.status
creating Makefile
creating xgap.sh

"..." indicate omissions. 
This script tries to determine, which kind of operating system and
libraries you have installed and configures the source
accordingly. Normally this should produce some output but no error
messages. The last step of the script produces some makefiles which are
used to compile the code. You do this by typing

# make
if test ! -d bin;  then mkdir bin;  fi
if test ! -d bin/i686-unknown-linux2.0.34-gcc; \ # line broken for this manual!
                then mkdir bin/i686-unknown-linux2.0.34-gcc;  fi
cp cnf/configure.out bin/i686-unknown-linux2.0.34-gcc/configure
( cd bin/i686-unknown-linux2.0.34-gcc ; CC=gcc \ # line broken for this manual!
                ./configure --target=i686-unknown-linux2.0.34  )
creating cache ./config.cache
checking for gcc... gcc
checking whether the C compiler (gcc  ) works... yes
checking whether the C compiler (gcc  ) is a cross-compiler... no
checking whether we are using GNU C... yes
...
creating ./config.status
creating Makefile
creating config.h
make[1]: Entering directory \                   # line broken for this manual!
     `/usr/local/lib/gap4/pkg/xgap/bin/i686-unknown-linux2.0.34-gcc'
gcc -I. -g -O2 -I/usr/X11R6/include  -o xcmds.o -c ../../src.x11/xcmds.c
gcc -I. -g -O2 -I/usr/X11R6/include  -o utils.o -c ../../src.x11/utils.c
...
make[1]: Leaving directory \                    # line broken for this manual!
     `/usr/local/lib/gap4/pkg/xgap/bin/i686-unknown-linux2.0.34-gcc'

(a few lines were broken for typesetting purposes in this manual, the
position is marked by a backslash) 

Now all C sources are compiled and a binary executable is built. It is
stored in a subdirectory of the "bin" subdirectory in your "xgap"
directory. The name of this location has something to do with your
installation. It could for example be

bin/i686-unknown-linux2.0.34-gcc/xgap

if you compile on a Linux system using the GNU-C-Compiler.


\Section{Installing the Startup Script}

To make the startup of XGAP more convenient there is a startup script
which contains also some configuration information like the position of
your GAP installation. It is in the "bin" directory within the
"xgap" tree and is called "xgap.sh". This file is automatically generated
by the `configure' script and normally you should *not* have to change 
anything in it. Just copy it to some location that people have in their
"PATH" environment variable, for example to "/usr/local/bin".
This completes the installation.

If you want to change anything in the installation, you
can also edit the script until the line

##  STOP EDITING HERE !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

You can specify the directory where GAP is installed "GAP_DIR", 
the amount of memory that GAP should use as initial workspace
("GAP_MEM"), the name of the GAP-executable ("GAP_PRG") and the
name of the XGAP-executable ("XGAP_PRG"). The first three are exactly 
the same things that you could edit in the main GAP startup script.
After that you have the possibility to control the behaviour of the XGAP
startup script. You can specify whether XGAP goes into the background
("DAEMON") and whether it prints out information about its parameters
("VERBOSE"). Note that it is possible to combine "DAEMON=YES"
and "VERBOSE=YES" because the script actually runs in the foreground and
only the C program is put into the background.


\Section{Installing in a different than the standard location}

It could happen that you do not want to install XGAP in its
standard location, perhaps because you do not want to bother your
system administrator and have no access to the GAP directory. In
this case you can unpack XGAP in any other location within a
"pkg" directory with the <unzoo> command as described above. Let us
call this directory "pkg" for the moment. You get an "xgap"
subdirectory with all the files of XGAP in it. You follow the
standard procedure with two exceptions:

Before you can configure and compile XGAP you need a symbolic link
"cnf" which is in the directory where "pkg" is and points to the "cnf"
directory in the main GAP directory. You can install this link directly
after unzooing by (remember: you are in the "pkg" directory!):

ln -s /usr/local/lib/gap4/cnf ..

if "/usr/local/lib/gap4" is the location of the main GAP installation.

You can find out where the main GAP4 installation is by starting
GAP as you usual and looking at the variable `GAP_ROOT_PATHS'
within GAP.

Note that you have to edit the startup script "xgap.sh" (see previous
section) to adjust the paths for "XGAP_DIR" and "GAP_DIR", and
possibly the name of the GAP executable "GAP_PRG".  Enter your GAP
installation directory for the variable "GAP_DIR" and the name of the
directory that contains "pkg" for the variable "XGAP_DIR". The
variable "GAP_PRG" has to contain the path to the GAP executable
relative to the "bin" subdirectory of the main GAP installation. In
most cases this value will already be correct. Note however that if
GAP and XGAP are compiled on different machines, then it is possible
that these directory names differ for the GAP and XGAP executables
respectively.

The script will automatically launch GAP with two directories as
library path such that all GAP and XGAP libraries will be found.


