# Install from Source Code¶

Some familiarity with the use of the Unix command line may be required to build Sage from the source code.

Building Sage from the source code has the major advantage that your install will be optimized for your particular computer and should therefore offer better performance and compatibility than a binary install.

Moreover, it offers you full development capabilities: you can change absolutely any part of Sage or the programs on which it depends, and recompile the modified parts.

See the file README.md in SAGE_ROOT for information on supported platforms and step-by-step instructions.

The following sections provide some additional details. Most users will not need to read them.

## Prerequisites¶

### General requirements¶

This section details the technical prerequisites needed on all platforms. See also the System-specific requirements below.

#### Disk space and memory¶

Your computer comes with at least 6 GB of free disk space. It is recommended to have at least 2 GB of RAM, but you might get away with less (be sure to have some swap space in this case).

#### Command-line tools¶

In addition to standard POSIX utilities and the bash shell, the following standard command-line development tools must be installed on your computer:

• A C/C++ compiler: Since SageMath builds its own GCC if needed, a wide variety of C/C++ compilers is supported. Many GCC versions work, from as old as version 4.8 (but we recommend at least 5.1) to the most recent release. Clang also works. See also Using alternative compilers.

• make: GNU make, version 3.80 or later. Version 3.82 or later is recommended.

• m4: GNU m4 1.4.2 or later (non-GNU or older versions might also work).

• perl: version 5.8.0 or later.

• ar and ranlib: can be obtained as part of GNU binutils.

• tar: GNU tar version 1.17 or later, or BSD tar.

• python: Python 3.4 or later, or Python 2.7. (This range of versions is a minimal requirement for internal purposes of the SageMath build system, which is referred to as sage-bootstrap-python.)

Other versions of these may work, but they are untested.

##### Fortran and compiler suites¶

Sage installation also needs a Fortran compiler. It is determined automatically whether Sage’s GCC package, or just its part containing Fortran compiler gfortran needs to be installed. This can be overwritten by running ./configure with option --without-system-gcc.

Officially we support gfortran from GNU Compiler Collection (GCC). If C and C++ compilers also come from there (i.e., gcc and g++), their versions should match. Alternatively, one may use C and C++ compilers from Clang: a C language family frontend for LLVM, and thus matching versions of clang, clang++ , along with a recent gfortran. (Flang (or other LLVM-based Fortran compilers) are not officially supported, however it is possible to to build Sage using flang, with some extra efforts needed to set various flags; this is work in progress at the moment (May 2019)).

Therefore, if you plan on using your own GCC compilers, then make sure that their versions match.

To force using specific compilers, set environment variables CC, CXX, and FC (for C, C++, and Fortran compilers, respectively) to the desired values, and run ./configure. For example, ./configure CC=clang CXX=clang++ FC=gfortran will configure Sage to be built with Clang C/C++ compilers and Fortran compiler gfortran.

Alternatively, Sage includes a GCC package, so that C, C++ and Fortran compilers will be built when the build system detects that it is needed, e.g., non-GCC compilers, or versions of the GCC compilers known to miscompile some components of Sage, or simply a missing Fortran compiler. In any case, you always need at least a C/C++ compiler to build the GCC package and its prerequisites before the compilers it provides can be used.

Note that you can always override this behavior through the configure options --without-system-gcc and --with-system-gcc, see Using alternative compilers.

There are some known problems with old assemblers, in particular when building the ecm and fflas_ffpack packages. You should ensure that your assembler understands all instructions for your processor. On Linux, this means you need a recent version of binutils; on macOS you need a recent version of Xcode.

#### Python for venv¶

By default, Sage will try to use system’s $$python3$$ to set up a virtual environment, a.k.a. venv rather than building a Python 3 installation from scratch. Use the configure option --without-system-python3 in case you want Python 3 built from scratch.

Sage will accept versions 3.7.x to 3.10.x.

You can also use --with-python=/path/to/python3_binary to tell Sage to use /path/to/python3_binary to set up the venv. Note that setting up venv requires a number of Python modules to be available within the Python in question. Currently, for Sage 9.6, these modules are as follows: sqlite3, ctypes, math, hashlib, crypt, socket, zlib, distutils.core, ssl - they will be checked for by the configure script.

#### Other notes¶

After extracting the Sage source tarball, the subdirectory upstream contains the source distributions for everything on which Sage depends.

If cloned from a git repository, the upstream tarballs will be downloaded, verified, and cached as part of the Sage installation process. We emphasize that all of this software is included with Sage, so you do not have to worry about trying to download and install any one of these packages (such as Python, for example) yourself.

When the Sage installation program is run, it will check that you have each of the above-listed prerequisites, and inform you of any that are missing, or have unsuitable versions.

### System-specific requirements¶

On macOS, there are various developer tools needed which may require some registration on Apple’s developer site; see macOS prerequisite installation.

On Redhat-derived systems not all perl components are installed by default and you might have to install the perl-ExtUtils-MakeMaker package.

On Cygwin, the lapack and liblapack-devel packages are required.

### Installing prerequisites¶

To check if you have the above prerequisites installed, for example perl, type:

$command -v perl  or: $ which perl


on the command line. If it gives an error (or returns nothing), then either perl is not installed, or it is installed but not in your PATH.

#### macOS prerequisite installation¶

On macOS systems, you need a recent version of Command Line Tools. It provides all the above requirements.

Run the command xcode-select --install from a Terminal window and click “Install” in the pop-up dialog box.

If you have already installed Xcode (which at the time of writing is freely available in the Mac App Store, or through https://developer.apple.com/downloads/ provided you registered for an Apple Developer account), you can install the command line tools from there as well.

If you have not installed Xcode you can get these tools as a relatively small download, but it does require a registration.

#### Cygwin prerequisite installation¶

Sage can be built only on the 64-bit version of Cygwin. See the file README.md in SAGE_ROOT for the most up-to-date instructions for building Sage on Cygwin.

Although it is possible to install Sage’s dependencies using the Cygwin graphical installer, it is recommended to install the apt-cyg command-line package installer, which is used for the remainder of these instructions. To run apt-cyg, you must have already installed (using the graphical installer) the following packages at a minimum:

bzip2 coreutils gawk gzip tar wget


With the exception of wget most of these are included in the default package selection when you install Cygwin. Then, to install apt-cyg run:

$curl -OL https://rawgit.com/transcode-open/apt-cyg/master/apt-cyg$ install apt-cyg /usr/local/bin
$rm -f apt-cyg  To install the current set of system packages known to work for building Sage, run: $ apt-cyg install R binutils bzip2 cddlib-devel cddlib-tools cmake curl findutils gcc-core gcc-fortran gcc-g++ gengetopt glpk libatomic_ops-devel libboost-devel libbz2-devel libcrypt-devel libcurl-devel libffi-devel libflint-devel libfreetype-devel libgc-devel libgd-devel libglpk-devel libgmp-devel libgsl-devel libiconv-devel liblapack-devel liblzma-devel libmpc-devel libmpfr-devel libncurses-devel libntl-devel libopenblas libpcre-devel libreadline-devel libsqlite3-devel libssl-devel libsuitesparseconfig-devel libtirpc-devel libzmq-devel m4 make patch perl perl-ExtUtils-MakeMaker python39 python39-devel python39-urllib3 qhull singular singular-devel sqlite3 tar which xz zlib-devel


Optional packages that are also known to be installable via system packages include:

  $apt-cyg install clang graphviz info lib4ti2-devel lib4ti2_0 libisl-devel libxml2-devel ninja perl-Term-ReadLine-Gnu  #### Ubuntu on Windows Subsystem for Linux (WSL) prerequisite installation¶ Sage can be installed onto Linux running on Windows Subsystem for Linux (WSL). These instructions describe a fresh install of Ubuntu 20.10, but other distributions or installation methods should work too, though have not been tested. • Enable hardware-assisted virtualization in the EFI or BIOS of your system. Refer to your system (or motherboard) maker’s documentation for instructions on how to do this. • Set up WSL by following the official WSL setup guide. Be sure to do the steps to install WSL2 and set it as default. • Go to the Microsoft Store and install Ubuntu. • Start Ubuntu from the start menu. Update all packages to the latest version. • Reboot the all running WSL instances one of the following ways: • Open Windows Services and restart the LxssManager service. • Open the Command Prompt or Powershell and enter this command: wsl --shutdown  • Upgrade to the Ubuntu 20.10. This step will not be necessary once Ubuntu 20.10 is available in the Microsoft Store. From this point on, follow the instructions in the Linux recommended installation section. It is strongly recommended to put the Sage source files in the Linux file system, for example, in the /home/username/sage directory, and not in the Windows file system (e.g. /mnt/c/...). You may encounter permission errors of the kind "[Errno 13] Permission denied: 'build/bdist.linux-x86_64/wheel/<package>.dist-info'" during make. This usually comes from a permission conflict between the Windows and Linux file system. To fix it create a temporary build folder in the Linux file system using mkdir -p ~/tmp/sage and use it for building by eval SAGE_BUILD_DIR="~/tmp/sage" make. Also see the related Github issue for other workarounds. When the installation is complete, you may be interested in WSL Post-installation steps. #### Other platforms¶ On Solaris, you would use pkgadd and on OpenSolaris ipf to install the necessary software. On other systems, check the documentation for your particular operating system. #### Notes on using conda¶ If you don’t want conda to be used by sage, deactivate conda (for the current shell session). • Type: $ conda deactivate

• Repeat the command until conda info shows:

$conda info active environment : None ...  Then SageMath will be built either using the compilers provided by the operating system, or its own compilers. ### Specific notes for make and tar¶ On macOS, the system-wide BSD tar supplied will build Sage, so there is no need to install the GNU tar. ### Using alternative compilers¶ Sage developers tend to use fairly recent versions of GCC. Nonetheless, the Sage build process on Linux should succeed with any reasonable C/C++ compiler; (we do not recommend GCC older than version 5.1). This is because Sage will build GCC first (if needed) and then use that newly built GCC to compile Sage. If you don’t want this and want to try building Sage with a different set of compilers, you need to pass Sage’s ./configure compiler names, via environment variables CC, CXX, and FC, for C, C++, and Fortran compilers, respectively, e.g. if you C compiler is clang, your C++ compiler is clang++, and your Fortran compiler is flang then you would need to run: $ CC=clang CXX=clang++ FC=flang ./configure


before running make. It is recommended that you inspect the output of ./configure in order to check that Sage will not try to build GCC. Namely, there should be lines like:

gcc-7.2.0 will not be installed (configure check)
...
gfortran-7.2.0 will not be installed (configure check)


indicating that Sage will not attempt to build gcc/g++/gfortran.

If you are interested in working on support for commercial compilers from HP, IBM, Intel, Sun/Oracle, etc, please email the sage-devel mailing list at https://groups.google.com/group/sage-devel.

### Tcl/Tk¶

If you want to use Tcl/Tk libraries in Sage, you need to install the Tcl/Tk and its development headers before building Sage. Sage’s Python will then automatically recognize your system’s install of Tcl/Tk.

On Linux systems, these are usually provided by the tk and tk-dev (or tk-devel) packages which can be installed using:

$sudo apt-get install tk tk-dev  or similar commands. If you installed Sage first, all is not lost. You just need to rebuild Sage’s Python and any part of Sage relying on it: $ sage -f python3  # rebuild Python3
$make # rebuild components of Sage depending on Python  after installing the Tcl/Tk development libraries as above. If sage: import _tkinter sage: import Tkinter  does not raise an ImportError, then it worked. ## Step-by-step installation procedure¶ ### General procedure¶ 1. Follow the procedure in the file README.md in SAGE_ROOT. 2. Additional remarks: You do not need to be logged in as root, since no files are changed outside of the sage-x.y directory. In fact, it is inadvisable to build Sage as root, as the root account should only be used when absolutely necessary and mistyped commands can have serious consequences if you are logged in as root. Typing make performs the usual steps for each Sage’s dependency, but installs all the resulting files into the local build tree. Depending on the age and the architecture of your system, it can take from a few tens of minutes to several hours to build Sage from source. On really slow hardware, it can even take a few days to build Sage. Each component of Sage has its own build log, saved in SAGE_ROOT/logs/pkgs. If the build of Sage fails, you will see a message mentioning which package(s) failed to build and the location of the log file for each failed package. If this happens, then paste the contents of these log file(s) to the Sage support newsgroup at https://groups.google.com/group/sage-support. If the log files are very large (and many are), then don’t paste the whole file, but make sure to include any error messages. It would also be helpful to include the type of operating system (Linux, macOS, Solaris, OpenSolaris, Cygwin, or any other system), the version and release date of that operating system and the version of the copy of Sage you are using. (There are no formal requirements for bug reports – just send them; we appreciate everything.) See Make targets for some targets for the make command and Environment variables for additional information on useful environment variables used by Sage. 3. To start Sage, you can now simply type from Sage’s home directory: $ ./sage


You should see the Sage prompt, which will look something like this:

$sage ┌────────────────────────────────────────────────────────────────────┐ │ SageMath version 8.8, Release Date: 2019-06-26 │ │ Using Python 3.7.3. Type "help()" for help. │ └────────────────────────────────────────────────────────────────────┘ sage:  Note that Sage should take well under a minute when it starts for the first time, but can take several minutes if the file system is slow or busy. Since Sage opens a lot of files, it is preferable to install Sage on a fast filesystem if possible. Just starting successfully tests that many of the components built correctly. Note that this should have been already automatically tested during the build process. If the above is not displayed (e.g., if you get a massive traceback), please report the problem, e.g., at https://groups.google.com/group/sage-support. After Sage has started, try a simple command: sage: 2 + 2 4  Or something slightly more complicated: sage: factor(2005) 5 * 401  4. Optional, but highly recommended: Test the install by typing ./sage --testall. This runs most examples in the source code and makes sure that they run exactly as claimed. To test all examples, use ./sage --testall --optional=all --long; this will run examples that take a long time, and those that depend on optional packages and software, e.g., Mathematica or Magma. Some (optional) examples will therefore likely fail. Alternatively, from within $SAGE_ROOT, you can type make test (respectively make ptest) to run all the standard test code serially (respectively in parallel).

Testing the Sage library can take from half an hour to several hours, depending on your hardware. On slow hardware building and testing Sage can even take several days!

5. Optional: Check the interfaces to any other software that you have available. Note that each interface calls its corresponding program by a particular name: Mathematica is invoked by calling math, Maple by calling maple, etc. The easiest way to change this name or perform other customizations is to create a redirection script in $SAGE_ROOT/local/bin. Sage inserts this directory at the front of your PATH, so your script may need to use an absolute path to avoid calling itself; also, your script should pass along all of its arguments. For example, a maple script might look like: #!/bin/sh exec /etc/maple10.2/maple.tty "[email protected]"  6. Optional: There are different possibilities to make using Sage a little easier: • Make a symbolic link from /usr/local/bin/sage (or another directory in your PATH) to $SAGE_ROOT/sage:

$ln -s /path/to/sage-x.y/sage /usr/local/bin/sage  Now simply typing sage from any directory should be sufficient to run Sage. • Copy $SAGE_ROOT/sage to a location in your PATH. If you do this, make sure you edit the line:

#SAGE_ROOT=/path/to/sage-version


at the beginning of the copied sage script according to the direction given there to something like:

SAGE_ROOT=<SAGE_ROOT>


(note that you have to change <SAGE_ROOT> above!). It is best to edit only the copy, not the original.

• For KDE users, create a bash script called sage containing the lines (note that you have to change <SAGE_ROOT> below!):

#!/usr/bin/env bash

konsole -T "sage" -e <SAGE_ROOT>/sage


make it executable:

$chmod a+x sage  and put it somewhere in your PATH. You can also make a KDE desktop icon with this line as the command (under the Application tab of the Properties of the icon, which you get my right clicking the mouse on the icon). • On Linux and macOS systems, you can make an alias to $SAGE_ROOT/sage. For example, put something similar to the following line in your .bashrc file:

alias sage=<SAGE_ROOT>/sage


(Note that you have to change <SAGE_ROOT> above!) Having done so, quit your terminal emulator and restart it. Now typing sage within your terminal emulator should start Sage.

7. Optional: Install optional Sage packages and databases. Type sage --optional to see a list of them (this requires an Internet connection), or visit https://www.sagemath.org/packages/optional/. Then type sage -i <package-name> to automatically download and install a given package.

8. Optional: Run the install_scripts command from within Sage to create GAP, GP, Maxima, Singular, etc., scripts in your PATH. Type install_scripts? in Sage for details.

9. Have fun! Discover some amazing conjectures!

Building on Cygwin will occasionally require “rebasing” dll files. Sage provides some scripts, located in $SAGE_LOCAL/bin, to do so: • sage-rebaseall.sh, a shell script which calls Cygwin’s rebaseall program. It must be run within a dash shell from the SAGE_ROOT directory after all other Cygwin processes have been shut down and needs write-access to the system-wide rebase database located at /etc/rebase.db.i386, which usually means administrator privileges. It updates the system-wide database and adds Sage dlls to it, so that subsequent calls to rebaseall will take them into account. • sage-rebase.sh, a shell script which calls Cygwin’s rebase program together with the -O/--oblivious option. It must be run within a shell from SAGE_ROOT directory. Contrary to the sage-rebaseall.sh script, it neither updates the system-wide database, nor adds Sage dlls to it. Therefore, subsequent calls to rebaseall will not take them into account. • sage-rebaseall.bat (respectively sage-rebase.bat), an MS-DOS batch file which calls the sage-rebaseall.sh (respectively sage-rebase.sh) script. It must be run from a Windows command prompt, after adjusting SAGE_ROOT to the Windows location of Sage’s home directory, and, if Cygwin is installed in a non-standard location, adjusting CYGWIN_ROOT as well. Some systems may encounter this problem frequently enough to make building or testing difficult. If executing the above scripts or directly calling rebaseall does not solve rebasing issues, deleting the system-wide database and then regenerating it from scratch, e.g., by executing sage-rebaseall.sh, might help. Finally, on Cygwin, one should also avoid the following: • building in home directories of Windows domain users; • building in paths with capital letters (see trac ticket #13343, although there has been some success doing so). ## Make targets¶ To build Sage from scratch, you would typically execute make in Sage’s home directory to build Sage and its HTML documentation. The make command is pretty smart, so if your build of Sage is interrupted, then running make again should cause it to pick up where it left off. The make command can also be given options, which control what is built and how it is built: • make build builds Sage: it compiles all of the Sage packages. It does not build the documentation. • make doc builds Sage’s documentation in HTML format. Note that this requires that Sage be built first, so it will automatically run make build first. Thus, running make doc is equivalent to running make. • make doc-pdf builds Sage’s documentation in PDF format. This also requires that Sage be built first, so it will automatically run make build. • make doc-html-no-plot builds Sage’s documentation in html format but skips the inclusion of graphics auto-generated using the .. PLOT markup and the sphinx_plot function. This is primarily intended for use when producing certain binary distributions of Sage, to lower the size of the distribution. As of this writing (December 2014, Sage 6.5), there are only a few such plots, adding about 4M to the local/share/doc/sage/ directory. In the future, this may grow, of course. Note: after using this, if you want to build the documentation and include the pictures, you should run make doc-uninstall, because the presence, or lack, of pictures is cached in the documentation output. You can benefit from this no-plot feature with other make targets by doing export SAGE_DOCBUILD_OPTS+=' --no-plot' • make ptest and make ptestlong: these run Sage’s test suite. The first version skips tests that need more than a few seconds to complete and those which depend on optional packages or additional software. The second version includes the former, and so it takes longer. The “p” in ptest stands for “parallel”: tests are run in parallel. If you want to run tests serially, you can use make test or make testlong instead. If you want to run tests depending on optional packages and additional software, you can use make testall, make ptestall, make testalllong, or make ptestalllong. • make doc-uninstall and make doc-clean each remove several directories which are produced when building the documentation. • make distclean restores the Sage directory to its state before doing any building: it is almost equivalent to deleting Sage’s entire home directory and unpacking the source tarfile again, the only difference being that the .git directory is preserved, so git branches are not deleted. ## Environment variables¶ Sage uses several environment variables to control its build process. Most users won’t need to set any of these: the build process just works on many platforms. (Note though that setting MAKE, as described below, can significantly speed up the process.) Building Sage involves building about 100 packages, each of which has its own compilation instructions. The Sage source tarball already includes the sources for all standard packages, that is, it allows you to build Sage without internet connection. The git repository, however, does not contain the source code for third-party packages. Instead, it will be downloaded as needed (Note: you can run make download to force downloading packages before building). Package downloads use the Sage mirror network, the nearest mirror will be determined automatically for you. This is influenced by the following environment variable: • SAGE_SERVER - Try the specified mirror first, before falling back to the official Sage mirror list. Note that Sage will search the directory • SAGE_SERVER/spkg/upstream for upstream tarballs. Here are some of the more commonly used variables affecting the build process: • MAKE - one useful setting for this variable when building Sage is MAKE='make -jNUM' to tell the make program to run NUM jobs in parallel when building. Note that some Sage packages may not support this variable. Some people advise using more jobs than there are CPU cores, at least if the system is not heavily loaded and has plenty of RAM; for example, a good setting for NUM might be between 1 and 1.5 times the number of cores. In addition, the -l option sets a load limit: MAKE='make -j4 -l5.5, for example, tells make to try to use four jobs, but to not start more than one job if the system load average is above 5.5. See the manual page for GNU make: Command-line options and Parallel building. Warning Some users on single-core macOS machines have reported problems when building Sage with MAKE='make -jNUM' with NUM greater than one. • SAGE_NUM_THREADS - if set to a number, then when building the documentation, parallel doctesting, or running sage -b, use this many threads. If this is not set, then determine the number of threads using the value of the MAKE (see above) or MAKEFLAGS environment variables. If none of these specifies a number of jobs, use one thread (except for parallel testing: there we use a default of the number of CPU cores, with a maximum of 8 and a minimum of 2). • V - if set to 0, silence the build. Instead of showing a detailed compilation log, only one line of output is shown at the beginning and at the end of the installation of each Sage package. To see even less output, use: $ make -s V=0


(Note that the above uses the syntax of setting a Makefile variable.)

• SAGE_CHECK - if set to yes, then during the build process, or when installing packages manually, run the test suite for each package which has one, and stop with an error if tests are failing. If set to warn, then only a warning is printed in this case. See also SAGE_CHECK_PACKAGES.

• SAGE_CHECK_PACKAGES - if SAGE_CHECK is set to yes, then the default behavior is to run test suites for all spkgs which contain them. If SAGE_CHECK_PACKAGES is set, it should be a comma-separated list of strings of the form package-name or !package-name. An entry package-name means to run the test suite for the named package regardless of the setting of SAGE_CHECK. An entry !package-name means to skip its test suite. So if this is set to ppl,!python3, then always run the test suite for PPL, but always skip the test suite for Python 3.

Note

As of Sage 9.1, the test suites for the Python 2 and 3 spkgs fail on most platforms. So when this variable is empty or unset, Sage uses a default of !python2,!python3.

• SAGE_INSTALL_GCC - Obsolete, do not use, to be removed

• SAGE_INSTALL_CCACHE - by default Sage doesn’t install ccache, however by setting SAGE_INSTALL_CCACHE=yes Sage will install ccache. Because the Sage distribution is quite large, the maximum cache is set to 4G. This can be changed by running sage -sh -c "ccache --max-size=SIZE", where SIZE is specified in gigabytes, megabytes, or kilobytes by appending a “G”, “M”, or “K”.

Sage does not include the sources for ccache since it is an optional package. Because of this, it is necessary to have an Internet connection while building ccache for Sage, so that Sage can pull down the necessary sources.

• SAGE_DEBUG - controls debugging support. There are three different possible values:

• Not set (or set to anything else than “yes” or “no”): build binaries with debugging symbols, but no special debug builds. This is the default. There is no performance impact, only additional disk space is used.

• SAGE_DEBUG=no: no means no debugging symbols (that is, no gcc -g), which saves some disk space.

• SAGE_DEBUG=yes: build debug versions if possible (in particular, Python is built with additional debugging turned on and Singular is built with a different memory manager). These will be notably slower but, for example, make it much easier to pinpoint memory allocation problems.

Instead of using SAGE_DEBUG one can configure with --enable-debug={no|symbols|yes}.

• SAGE_PROFILE - controls profiling support. If this is set to yes, profiling support is enabled where possible. Note that Python-level profiling is always available; This option enables profiling in Cython modules.

• SAGE_SPKG_INSTALL_DOCS - if set to yes, then install package-specific documentation to $SAGE_ROOT/local/share/doc/PACKAGE_NAME/ when an spkg is installed. This option may not be supported by all spkgs. Some spkgs might also assume that certain programs are available on the system (for example, latex or pdflatex). • SAGE_DOCBUILD_OPTS - the value of this variable is passed as an argument to sage --docbuild all html or sage --docbuild all pdf when you run make, make doc, or make doc-pdf. For example, you can add --no-plot to this variable to avoid building the graphics coming from the .. PLOT directive within the documentation, or you can add --include-tests-blocks to include all “TESTS” blocks in the reference manual. Run sage --docbuild help to see the full list of options. • SAGE_BUILD_DIR - the default behavior is to build each spkg in a subdirectory of $SAGE_ROOT/local/var/tmp/sage/build/; for example, build version 7.27.0 of ipython in the directory $SAGE_ROOT/local/var/tmp/sage/build/ipython-7.27.0/. If this variable is set, then build in $SAGE_BUILD_DIR/ipython-7.27.0/ instead. If the directory $SAGE_BUILD_DIR does not exist, it is created. As of this writing (Sage 4.8), when building the standard Sage packages, 1.5 gigabytes of free space are required in this directory (or more if SAGE_KEEP_BUILT_SPKGS=yes – see below); the exact amount of required space varies from platform to platform. For example, the block size of the file system will affect the amount of space used, since some spkgs contain many small files. Warning The variable SAGE_BUILD_DIR must be set to the full path name of either an existing directory for which the user has write permissions, or to the full path name of a nonexistent directory which the user has permission to create. The path name must contain no spaces. • SAGE_KEEP_BUILT_SPKGS - the default behavior is to delete each build directory – the appropriate subdirectory of $SAGE_ROOT/local/var/tmp/sage/build or $SAGE_BUILD_DIR – after each spkg is successfully built, and to keep it if there were errors installing the spkg. Set this variable to yes to keep the subdirectory regardless. Furthermore, if you install an spkg for which there is already a corresponding subdirectory, for example left over from a previous build, then the default behavior is to delete that old subdirectory. If this variable is set to yes, then the old subdirectory is moved to $SAGE_ROOT/local/var/tmp/sage/build/old/ (or $SAGE_BUILD_DIR/old), overwriting any already existing file or directory with the same name. Note After a full build of Sage (as of version 4.8), these subdirectories can take up to 6 gigabytes of storage, in total, depending on the platform and the block size of the file system. If you always set this variable to yes, it can take even more space: rebuilding every spkg would use double the amount of space, and any upgrades to spkgs would create still more directories, using still more space. Note In an existing Sage installation, running sage -i -s <package-name> or sage -f -s <package-name> installs the spkg <package-name> and keeps the corresponding build directory; thus setting SAGE_KEEP_BUILT_SPKGS to yes mimics this behavior when building Sage from scratch or when installing individual spkgs. So you can set this variable to yes instead of using the -s flag for sage -i and sage -f. • SAGE_FAT_BINARY - to build binaries that will run on the widest range of target CPUs set this variable to yes before building Sage or configure with --enable-fat-binary. This does not make the binaries relocatable, it only avoids newer CPU instruction set extensions. For relocatable (=can be moved to a different directory) binaries, you must use https://github.com/sagemath/binary-pkg • SAGE_SUDO - set this to sudo -E or to any other command prefix that is necessary to write into a installation hierarchy (SAGE_LOCAL) owned by root or another user. Note that this command needs to preserve environment variable settings (plain sudo does not). Not all Sage packages currently support SAGE_SUDO. Therefore this environment variable is most useful when a system administrator wishes to install an additional Sage package that supports SAGE_SUDO, into a root-owned installation hierarchy (SAGE_LOCAL). Environment variables dealing with specific Sage packages: • SAGE_MATPLOTLIB_GUI - if set to anything non-empty except no, then Sage will attempt to build the graphical backend when it builds the matplotlib package. • PARI_CONFIGURE - use this to pass extra parameters to PARI’s Configure script, for example to specify graphics support (which is disabled by default). See the file build/pkgs/pari/spkg-install for more information. • SAGE_TUNE_PARI: If yes, enable PARI self-tuning. Note that this can be time-consuming. If you set this variable to “yes”, you will also see this: WARNING: Tuning PARI/GP is unreliable. You may find your build of PARI fails, or PARI/GP does not work properly once built. We recommend to build this package with SAGE_CHECK="yes". • PARI_MAKEFLAGS: The value of this variable is passed as an argument to the $MAKE command when compiling PARI.

Some standard environment variables which are used by Sage:

• CC - while some programs allow you to use this to specify your C compiler, not every Sage package recognizes this. If GCC is installed within Sage, CC is ignored and Sage’s gcc is used instead.

• CPP - similarly, this will set the C preprocessor for some Sage packages, and similarly, using it is likely quite risky. If GCC is installed within Sage, CPP is ignored and Sage’s cpp is used instead.

• CXX - similarly, this will set the C++ compiler for some Sage packages, and similarly, using it is likely quite risky. If GCC is installed within Sage, CXX is ignored and Sage’s g++ is used instead.

• FC - similarly, this will set the Fortran compiler. This is supported by all Sage packages which have Fortran code. However, for historical reasons, the value is hardcoded during the initial make and subsequent changes to $FC might be ignored (in which case, the original value will be used instead). If GCC is installed within Sage, FC is ignored and Sage’s gfortran is used instead. • CFLAGS, CXXFLAGS and FCFLAGS - the flags for the C compiler, the C++ compiler and the Fortran compiler, respectively. The same comments apply to these: setting them may cause problems, because they are not universally respected among the Sage packages. Note also that export CFLAGS="" does not have the same effect as unset CFLAGS. The latter is preferable. • Similar comments apply to other compiler and linker flags like CPPFLAGS, LDFLAGS, CXXFLAG64, LDFLAG64, and LD. • OPENBLAS_CONFIGURE - adds additional configuration flags for the OpenBLAS package that gets added to the make command. (see trac ticket #23272) Sage uses the following environment variables when it runs: • DOT_SAGE - this is the directory, to which the user has read and write access, where Sage stores a number of files. The default location is $HOME/.sage/.

• SAGE_STARTUP_FILE - a file including commands to be executed every time Sage starts. The default value is $DOT_SAGE/init.sage. • BROWSER - on most platforms, Sage will detect the command to run a web browser, but if this doesn’t seem to work on your machine, set this variable to the appropriate command. Variables dealing with doctesting: • SAGE_TIMEOUT - used for Sage’s doctesting: the number of seconds to allow a doctest before timing it out. If this isn’t set, the default is 300 seconds (5 minutes). • SAGE_TIMEOUT_LONG - used for Sage’s doctesting: the number of seconds to allow a doctest before timing it out, if tests are run using sage -t --long. If this isn’t set, the default is 1800 seconds (30 minutes). • SAGE_TEST_GLOBAL_ITER, SAGE_TEST_ITER: these can be used instead of passing the flags --global-iterations and --file-iterations, respectively, to sage -t. Indeed, these variables are only used if the flags are unset. Run sage -t -h for more information on the effects of these flags (and therefore these variables). Sage sets some other environment variables. The most accurate way to see what Sage does is to first run env from a shell prompt to see what environment variables you have set. Then run sage --sh -c env to see the list after Sage sets its variables. (This runs a separate shell, executes the shell command env, and then exits that shell, so after running this, your settings will be restored.) Alternatively, you can peruse the shell script src/bin/sage-env. Sage also has some environment-like settings. Some of these correspond to actual environment variables while others have names like environment variables but are only available while Sage is running. To see a list, execute sage.env.[TAB] while running Sage. ## Installation in a Multiuser Environment¶ This section addresses the question of how a system administrator can install a single copy of Sage in a multi-user computer network. ### System-wide install¶ In the instructions below, we assume that /path/to/sage-x.y is the directory where you want to install Sage. 1. First of all, extract the Sage source tarball in /path/to (this will create the directory /path/to/sage-x.y). After extracting, you can change the directory name if you do not like sage-x.y. 2. Change the ownership of the /path/to/sage-x.y directory tree to your normal user account (as opposed to root). This is because Sage will refuse to compile as root. $ chown -R user:group /path/to/sage-x.y

3. Using your normal user account, build Sage. See the Step-by-step installation procedure above.

4. Make a symbolic link to the sage script in /usr/local/bin:

$ln -s /path/to/sage-x.y/sage /usr/local/bin/sage  Alternatively, copy the Sage script: $ cp /path/to/sage-x.y/sage /usr/local/bin/sage


If you do this, make sure you edit the line:

#SAGE_ROOT=/path/to/sage-version


at the beginning of the copied sage script according to the direction given there to something like:

SAGE_ROOT=<SAGE_ROOT>


(note that you have to change <SAGE_ROOT> above!). It is recommended not to edit the original sage script, only the copy at /usr/local/bin/sage.

5. Optionally, you can test Sage by running:

\$ make testlong


or make ptestlong which tests files in parallel using multiple processes. You can also omit long to skip tests which take a long time.