Linux

To install development tools on a Linux system, use your preferred package manager (e.g. apt-get or aptitude or Synaptic etc.). You need a working C and C++ development environment on your system as well as GNU make.

Note that to obtain a fully functional GAP installation you need not only to compile the core system, but also some of its packages. To install GAP using the source distribution, perform the following steps:

Verify that all required tools are installed. For example, on Ubuntu or Debian do this by calling
```
 sudo apt-get install build-essential autoconf libtool libgmp-dev libreadline-dev zlib1g-dev
```

Choose your preferred archive format and download the corresponding archive.

gap-4.13.1.tar.gz	515 MB	sha256: `9794dbdba6fb998e0a2d0aa8ce21fc8848ad3d3f9cc9993b0b8e20be7e1dbeba`
gap-4.13.1.zip	533 MB	sha256: `8298f4a8c78197d8509f01a1f841a09eaac4880dab273fae2ba82bc30eb69aa8`

Unpack the archive.
Compile the GAP core system by running
```
./configure && make
```
in the unpacked directory.
Change to the pkg subdirectory and call
```
../bin/BuildPackages.sh
```
to run the script which will build most of the packages that require compilation (provided sufficiently many libraries, headers and tools are available). If something doesn’t work on your system, please refer to the README file provided with the corresponding package.
Adjust some links/scripts/icons etc., to make the new version of GAP available to the users of your machine.
Optional: run a few tests.

Alternatives

Frank Lübeck offers a Linux binary distribution via remote syncronization with a reference installation which includes all packages and some optimisations.

GAP is available for installation in several package managers. A good overview of available GAP packages is available on this repology project page.