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  1. Installation Overview
  2. Getting the Archive
  3. Unpacking
  4. Compilation
  5. Configure options
  6. Testing the installation
  7. Packages
  8. Finish Installation and Cleanup
  9. The Documentation
  10. If Things Go Wrong
  11. Known Problems of the Configure Process
  12. Optimisation and Compiler Options
  13. GAP for macOS
  14. Expert Windows Installation

These are the installation instructions for the GAP source distribution on Unix (which covers Linux and macOS), and for the GAP binary distribution for Windows.

Alternative installation methods which aim to simplify the installation mostly by offering precompiled binaries are:

  • GAP installer for Homebrew (package manager for macOS)
  • Docker image for GAP and most of the packages
  • the rsync-based binary distribution for Linux

Note, however, that these are updated independently and may not yet provide the latest GAP release. Further details are available on the GAP website here:

1 Installation Overview

The GAP source distribution is designed to be installed in a similar way on a wide range of operating systems and to allow for considerable customisation of the installation to meet specific system needs. As a result, it may differ from what you would expect under your particular operating system. In particular, it does not include an automatic installer program.

Installing the GAP distribution with all the packages and full data libraries will require (except on Windows) both a C and a C++ compiler (gcc or clang is recommended) to be installed on your system. Please also consult section "Installing required dependencies" in the file

To get maximum benefit from GAP and from various packages, we recommend to install a number of other free software libraries (and their associated development tools) although they are not required for basic operation. See for more details.

The installation consists of five easy steps:

  1. Get the archive suitable for your system
  2. Unpack the archive in the directory where you wish to install GAP If you are reading this file as part of a GAP installation, you have probably already done this.
  3. Compile the kernel (unless a binary has been provided already)
  4. Test the installation
  5. Compile the packages that require it. (some of them will only work under Unix).

Installation will always install the new version of GAP. If you are worried about losing the old version, you can keep an existing installation of GAP in another directory, it will not be overwritten. Make sure, however, to adjust any links or scripts so that you run the latest version.

Section "The Documentation" below contains information about the manual, where to find and how to print it. Section "If Things Go Wrong" below lists common problems with the installation.

2 Getting the Archive

You can get archives for the GAP distribution from the GAP website at If you use Unix (including macOS), you need to download the GAP source distribution, that is, a file named


for GAP 4.X.Y. Alternatively, you can also use the .tar.gz or .zip archives.

If you use Windows, then download the .exe installer which contains binaries for GAP and some packages and provides the standard installation procedure.

3 Unpacking

The exact method of unpacking will vary dependently on the operating system and the type of archive used.

Unix (including macOS)

Under Unix style operating systems (such as Linux and macOS), unpack the archive gap-4.X.Y.tar.bz2 in whatever place you want GAP to reside. It will expand into a directory named gap-4.X.Y.

(If you unpack the archive as root user under Unix, make sure that you issue the command umask 022 before, to ensure that users will have permissions to read the files.)


If you are using the .exe installer, simply download and run it. It will offer a standard installation procedure, during which you will be able to select installation path.

Note that the path to the GAP directory must not contain spaces. For example, you may install it in a directory named like C:\gap-4.X.Y (default), D:\gap or C:\Math\GAP\my-gap-4.X.Y, but you must not install it in a directory named like C:\Users\alice\My Documents\gap-4.X.Y or C:\Program files\gap-4.X.Y etc.

4 Compilation

For the Windows version the unpacking process will already have put binaries in place. Under Unix you will have to compile such a binary yourself. (macOS users: please see section "GAP for macOS" below for additional information about compilation)

Change to the directory gap-4.X.Y (which you just created by unpacking). To get started quickly you may simply build GAP with default settings by issuing the two commands


(note that on BSD systems you have to call gmake instead of make).

Both will produce a lot of text output. You should end up with a shell script bin/ which you can use to start GAP. If you want, you can copy this script later to a directory that is listed in your search path.

macOS users please note that this script must be started from within the Terminal Application. It is not possible to start GAP by clicking this script.

If you get strange error messages from these commands, make sure that you got the Unix version of GAP (i.e. not the format archive) and that you extracted the archive on the same machine on which you compile. See also the section "Known Problems of the Configure Process" below.

5 Configure options

There are several options to the build process which you can specify at the configure step. The following paragraphs describe these options; a brief description of each is also available via

./configure --help


GAP 4 uses the external library GMP (see for large integer arithmetic, replacing the built-in code used in previous versions and achieving a significant speed-up in related computations. There is a version of GMP included with the GAP archive you downloaded and this will be used if GAP does not find a version of GMP already installed on your system. You can configure which GMP GAP uses as follows:

./configure --with-gmp=builtin|PREFIX

If this option is not given, GAP will try to find a suitable version of GMP can be found using the specified CPPFLAGS, CFLAGS and LDFLAGS. If not, it will fallback to compiling its own version of GMP.

You can force GAP to build its own copy of GMP by passing --with-gmp=builtin. Finally, you pass a prefix path where GAP should search for a copy of GMP; i.e., --with-gmp=PREFIX instructs GAP to search for the header file gmp.h in PREFIX/includes, and the library itself in PREFIX/lib.

For historical reasons, you may also pass --with-gmp=system, which is simply ignored by GAP (i.e., the default behavior described above is used).


GAP optionally also uses the external library GNU Readline (see for better command line editing. GAP will use this library by default if it is available on your system. You can configure Readline use as follows:

./configure --with-readline=yes|no|"path"

If the argument you supply is yes, then GAP will look in standard locations for a Readline installed on your system. Or you can specify a path to a Readline installation. If the supplied argument is no then readline support will not be used.

Note that --with-readline is equivalent to --with-readline=yes and --without-readline is equivalent to --with-readline=no.

There was an annoying bug in the readline library on macOS which made pasting text very slow. If you have that version of the readline library, this delay be avoided by pressing a key (e.g. space) during the paste, or you may prefer to build GAP without readline to avoid this issue entirely.

Build 32-bit vs. 64-bit binaries

GAP will attempt to build in 32-bit mode on 32-bit machines and in 64-bit mode on 64-bit machines. On a 64-bit machine, you can tell GAP to build in 32-bit instead, if you wish. In that case, GMP will also be built in 32-bit mode. You can configure the build mode as follows:

./configure ABI=32


./configure ABI=64

The value of the argument determines the build mode GAP will attempt to use. Note that building in 64-bit mode on a 32-bit architecture is not supported.

It is possible (on a 64-bit machine) to have builds in both 32- and 64-bit modes using "out of tree builds". For details, please refer to the file

6 Testing the installation

You are now at a point where you can start GAP for the first time. Unix users (including those on macOS) should type


Windows users should start GAP with the batch file


GAP should start up with its banner and after a little while give you a command prompt


Try a few commands to see if the compilation succeeded.

gap> 2 * 3 + 4;
gap> Factorial( 30 );
gap> m11 := Group((1,2,3,4,5,6,7,8,9,10,11),(3,7,11,8)(4,10,5,6));;
gap> Size( m11 );
gap> Length( ConjugacyClasses( m11 ) );
gap> Factors( 10^42 + 1 );
[ 29, 101, 281, 9901, 226549, 121499449, 4458192223320340849 ]

If you get the error message hmm, I cannot find lib/init.g you are likely to have installed only the binary (or used the wrong path on Windows).

If GAP starts but you get error messages for the commands you issued, the files in the lib directory are likely to be corrupt or incomplete. Make sure that you used the proper archive and that extraction proceeded without errors.

Especially try the command line editing and history facilities, because they are probably the most machine dependent feature of GAP. Enter a few commands and then make sure that Ctrl-P redisplays the last command, that Ctrl-E moves the cursor to the end of the line, that Ctrl-B moves the cursor back one character, and that Ctrl-D deletes single characters. So, after entering the above commands, typing

Ctrl-P  Ctrl-E  Ctrl-B  Ctrl-B  Ctrl-B  Ctrl-B  Ctrl-D  2  Return

should give the following lines:

gap> Factors( 10^42 + 2 );
[ 2, 3, 433, 953, 128400049, 3145594690908701990242740067 ]

If you want to run a quick test of your GAP installation (though this is not required), you can read in a test script that exercises some GAP's capabilities. To run this test, we recommend to use a computer with at least 1 GB of memory; on an up-to-date desktop computer, it should complete in about a minute. You will get a large number of lines with output about the progress of the tests, for example:

gap> Read( Filename( DirectoriesLibrary( "tst" ), "testinstall.g" ) );
Architecture: SOMETHING-SOMETHING-gcc-default64

testing: ..../gap-4.X.Y/tst/testinstall/alghom.tst
      84 ms (55 ms GC) and 2.90MB allocated for alghom.tst
testing: ..../gap-4.X.Y/tst/testinstall/algmat.tst
     839 ms (114 ms GC) and 219MB allocated for algmat.tst
[ further lines deleted ]
testing: ..../gap-4.X.Y/tst/testinstall/zmodnze.tst
     127 ms (119 ms GC) and 1.29MB allocated for zmodnze.tst
total     62829 ms (24136 ms GC) and 8.61GB allocated
              0 failures in 252 files

#I  No errors detected while testing

GAP will exit after this test with the corresponding exit code (this is useful for automated testing). If you want to run a more advanced check (this is not required and may take up to an hour), you can start a new GAP session and read teststandard.g which is an extended test script performing all tests from the tst directory.

gap> Read( Filename( DirectoriesLibrary( "tst" ), "teststandard.g" ) );

Again we recommend a computer with at least 1 GB of memory to run this test. It takes significantly longer to complete than testinstall.g, but otherwise produces output similar to the testinstall.g test.

Windows users should note that the Command Prompt user interface provided by Microsoft might not offer history scrolling or cut and paste with the mouse. To get a better environment, use the script gap.bat to start GAP instead of gapcmd.bat.

7 Packages

The GAP distribution already contains all the GAP packages which we redistribute in the gap-4.X.Y/pkg directory, and for packages that consist only of GAP code no further installation is necessary.

Some packages however contain external binaries that will require separate compilation. (If you use Windows you may not be able to use external binaries anyhow, except for those packages whose binaries for Windows are included in their distribution, so you may skip the rest of this section.) You can skip this compilation now and do it later -- GAP will work fine, but the capabilities of the affected packages won't be available.

In general, each package contains a README file that contains information about the package and the necessary installation. Typically, for a package that requires compilation, the installation steps consist of changing to the packages directory and issuing the commands ./configure && make in the packages directory. This has to be done separately for every package, and their README files should tell exactly which commands to use.

To help with this tedious process, we ship a shell script called bin/ that will compile most of the packages that require compilation on Unix systems (including Linux and macOS) with sufficiently many libraries, headers and tools available. To use it, change to the gap-4.X.Y/pkg directory and execute the script like this:


If you have problems with package installations please contact the package authors as listed in the packages README file. Many GAP packages have their own development repositories and issue trackers, details of which could be found at

8 Finish Installation and Cleanup

Congratulations, your installation is finished.

Once the installation is complete, we would like to ask you to send us a short note to, telling us about the installation. (This is just a courtesy; we like to know how many people are using GAP and get feedback regarding difficulties (hopefully none) that users may have had with installation.)

We also suggest that you subscribe to our GAP Forum mailing list; see the GAP web pages for details. Whenever there is a bug fix or new release of GAP this is where it is announced. The GAP Forum also deals with user questions of a general nature; bug reports and other problems you have while installing and/or using GAP should be sent to

If you are new to GAP, you might want to read through the following two sections for information about the documentation.

9 The Documentation

The GAP documentation is distributed in various "books". The standard distribution contains two of them. GAP packages (see Chapter "GAP Packages" of the GAP Reference manual and, in particular, the Section "Loading a GAP Package") provide their own documentation in their own doc directories.

All documentation will be available automatically within every GAP session (see Section "Help" of the GAP Tutorial and Chapter "The Help System" in the GAP Reference manual).

There also is (if installed) an HTML version of some books that can be viewed with an HTML browser, see Section "Changing the Help Viewer" of the GAP Reference manual.

The manual is also available in pdf format. In the full distribution these files are included in the directory gap-4.X.Y/doc in the subdirectories tut (a beginner's tutorial), ref (the reference manual), and hpc (HPC-GAP reference manual).

If you want to use these manual files with the help system from your GAP session you may check (or make sure) that your system provides some additional software like xpdf or acroread.

To complete beginners, we suggest you read (parts of) the tutorial first for an introduction to GAP 4. Then start to use the system with extensive use of the help system (see Section "Help" of the GAP Tutorial and Chapter "The Help System" in the GAP Reference manual).

As some of the manuals are quite large, you should not immediately print them. If you start using GAP it can be helpful to print the tutorial (and probably the first chapters of the reference manual). There is no compelling reason to print the whole of the reference manual, better use the help system which provides useful search features.

10 If Things Go Wrong

This section lists a few common problems when installing or running GAP and their remedies. Also see the FAQ list on the GAP web pages at

GAP starts with a warning hmm, I cannot find lib/init.g

You either started only the binary or did not edit the shell script/batch file to give the correct library path. You must start the binary with the command line option

-l <path>

where <path> is the path to the GAP home directory (see Section "Command Line Options" of the GAP Reference manual).

When starting, GAP produces error messages about undefined variables.

You might have a .gaprc file in your home directory that was used by GAP 4.4 but is not compatible with later releases. See section "The gap.ini and gaprc files" in Section "Running GAP" of the GAP Reference manual.

GAP stops with an error message exceeded the permitted memory.

Your job required more memory than is permitted by default (this is a safety feature to avoid single jobs wrecking a multi-user system.) You can type return; to continue, if the error message happens repeatedly it might be better to start the job anew and use the command line option -o to set a higher memory limit.

GAP stops with an error message: cannot extend the workspace any more.

Your calculation exceeded the available memory. Most likely you asked GAP to do something which required more memory than you have (as listing all elements of S_15 for example). You can use the command line option -g (see Section "Command Line Options" of the GAP Reference manual) to display how much memory GAP uses. If this is below what your machine has available extending the workspace is impossible. Start GAP with more memory using the -o option.

GAP is not able to allocate memory above a certain limit

In a 32-bit mode GAP is unable to use over 4 GB of memory. In fact, since some address space is needed for system purposes, it is likely that GAP sessions will be limited to 3 GB or even less.

Depending on the operating system, it also might be necessary to compile the GAP binary statically (i.e. to include all system libraries) to avoid collisions with system libraries located by default at an address within the workspace. (Under Linux for example, 1 GB is a typical limit.) You can compile a static binary using make static.

Recompilation fails or the new binary crashes.

Call make clean and restart the configure / make process completely from scratch. (It is possible that the operating system and/or compiler got upgraded in the meantime and so the existing .o files cannot be used any longer.

A calculation runs into an error no method found.

GAP is not able to execute a certain operation with the given arguments. Besides the possibility of bugs in the library this means two things: Either GAP truly is incapable of coping with this task (the objects might be too complicated for the existing algorithms or there might be no algorithm that can cope with the input). Another possibility is that GAP does not know that the objects have certain nice properties (like being finite) which are required for the available algorithms. See section "ApplicableMethod" and "KnownPropertiesOfObject" of the GAP Reference manual.

The ^-key or "-key cannot be entered.

This is a problem if you are running a keyboard driver for some non-english languages. These drivers catch the ^ character to produce the French circumflex accent and do not pass it properly to GAP. For macOS users, as a workaround please refer to the section "GAP for macOS" below for information on how to install readline and section 5 on how to recompile GAP, for windows no fix is known. (One can type POW(a,b) for a^b.)

Problems specific to Windows

Cut and Paste does not work

You might want to try different shells, using both of the two .bat files in the bin directory: gap.bat and gapcmd.bat. Also, might give a remedy.

GAP does not work in the remote desktop

GAP cannot be started in the Windows Command Prompt shell (via gapcmd.bat) in the remote desktop. To start GAP in the remote desktop, use the script gap.bat which should work in such setting.

You get an error message about the cygwin1.dll

GAP comes with a version of this dynamic library. If you have another version installed (use "Find"), delete the older one (and probably copy the newer one in both places).

Something else went wrong

If all these remedies fail or you encountered a bug please send a mail to Please give:

  • a (short, if possible) self-contained excerpt of a GAP session containing both input and output that illustrates your problem (including comments of why you think it is a bug); and

  • state the type of machine, the operating system, which compiler you used (if any), and the version of GAP you are using (the line from the GAP banner starting with

      GAP, Version 4.X.Y...

    when GAP starts up, supplies the information required).

11 Known Problems of the Configure Process

The configure script respects compiler settings given in environment variables. However such settings may conflict with the automatic configuration process. If configure produces strange error messages about not being able to run the compiler, check whether environment variables that might affect the compilation (in particular CC, CXX, CPP, LD, CFLAGS, CXXFLAGS, CPPFLAGS and LDFLAGS) are set and reset them using unsetenv.

12 Optimization and Compiler Options

Because of the large variety of different versions of Unix and different compilers it is possible that the configure process will not chose best possible optimisation level, but you might need to tell make about it.

If you want to compile GAP with further compiler options (for example specific processor optimisations) you will have to assign them to the variables CFLAGS, CXXFLAGS, CPPFLAGS and LDFLAGS, then re-run configure and make.

If there are several compiler options or if they contain spaces you might have to enclose them by quotes depending on the shell you are using.

The configure process also introduces some default compiler options. You can eliminate these by assigning the replacement options to the variable CFLAGS.

The recommended C/C++ compiler for GAP is the GNU C compiler gcc version 4.8 or later. The Clang compiler version 3.0 and later also should work fine. If you use another compiler, please let us know your experience with using it to compile GAP.

If you do wish to use GAP with a specific compiler, you can set the environment variables CC resp. CXX to the name of your preferred C resp. C++ compiler and then rerun configure and make.

As an example, here is how one can configure GAP to compile with Clang 5 (assuming it is installed on your system), with custom compiler flags and debug mode enabled:

./configure CC=clang-5.0 CXX=clang++-5.0 CFLAGS="-g -Og" CXXFLAGS="-g -Og" --enable-debug

13 GAP for macOS

Currently we provide no precompiled binary distribution for macOS. However, since macOS is an operating system in the Unix family, you can follow the Unix installation guidelines to compile GAP; then you will be able to use all features of GAP as well as all packages. However for installation you might need a basic knowledge of Unix.

The following are a couple of notes and remarks about this:

First, note that you should get the Unix type GAP archives, i.e. one of .zip, .tar.gz or .tar.bz2 archives, but not the archive (you won't be able to compile the program as given in the archive).

To compile and run GAP you will have to open the Terminal application and type the necessary Unix commands into its window. The Terminal application can be found in the Utilities folder in the Applications folder.

Next, you will need a compiler and build tools like make. These tools are included in the "Xcode" application which is not installed by default on a new Mac. On all recent versions of macOS, you can install it for free via the App Store. Afterwards, you also need to run the following command from a terminal in order to make all required tools available via the command line:

 xcode-select --install

You might want to consider using GNU readline by installing it via:

  • using Homebrew: brew install readline
  • using Fink: fink install readline7
  • using MacPorts: port install readline

After that you have to compile GAP and tell it where to find your installation of GNU readline using the following commands.

For Homebrew, use these commands:

./configure --with-readline=$(brew --prefix)/opt/readline

For Fink, use these commands:

./configure CPPFLAGS=-I/sw/include LDFLAGS=-L/sw/lib

For MacPorts, use these commands:

./configure CPPFLAGS=-I/opt/local/include LDFLAGS=-L/opt/local/lib

For further information on how to use GNU readline, refer to section 5 above.

Now simply follow the Unix installation instructions to compile and start GAP and then it will run in this Terminal window.

14 Expert Windows Installation

Instead of using the .exe installer, you may use the archive, which you may unpack with an appropriate extractor. The content of the latter archive is identical to the content of the former one, except that there is no installation procedure and you may have to edit the *.bat files yourself.

The archive already contains *.bat files which will work if GAP is installed in the standard location, which is C:\gap-4.X.Y. To install GAP there, the archive must be extracted to the main directory of the C: drive. Make sure that you specify extraction to the C:\ folder (with no extra directory name -- the directory gap-4.X.Y is part of the archive) to avoid extraction in a wrong place or in a separate directory.

After extraction you can start GAP with one of the following files:

C:\gap-4.X.Y\bin\gap.bat       (recommended)

The gap.bat file will start GAP in the mintty shell. It allows for convenient copying and pasting (e.g. using mouse) and flexible customisation. Using its "Options" menu, accessible by the right-click on the pictogram in its top left corner, you may adjust the font and colour scheme as you prefer. Note that gap.bat will open two windows - one actually running GAP and an auxiliary one, which may be minimised but should not be closed (otherwise the GAP session will be terminated).

If you need to install GAP in a non-standard directory under Windows, we advise to use the Windows .exe installers which will adjust all paths in batch files during the installation. Whenever you use a Windows installer or install GAP from the archive, you should avoid paths with spaces, e.g. do not use C:\My Programs\gap-4.X.Y. If you need to install GAP on another logical drive, say E:, the easiest way would be just to use E:\gap-4.X.Y.

If you need to edit a *.bat file to specify the path to your GAP installation manually, you will have to replace substrings /c/gap-4.X.Y/ by the actual path to the GAP root directory in the Unix format, and substrings C:\gap-4.X.Y\ by the actual path to the GAP root directory in the Windows format. Please avoid introducing new line breaks when editing (i.e. do not use a text editor which automatically wraps long lines).

Please contact if you need further information.

Wishing you fun and success using GAP,

The GAP Group