ISIS Installation Guide ======================= John C. Houck {backend@xhtml11:Last updated\: {revdate}} For more information about isis, see: http://space.mit.edu/cxc/isis/ Send bug reports, comments and suggestions to: isis-users@space.mit.edu Overview -------- ***************************************************************** The easiest way to set up a new isis installation is to run an installation script that will automatically download and install isis and a few commonly used modules. This installation method is documented in Part I, <>. For those who prefer greater control and customization, full details of the isis installation process are documented in Part II, <>. Once isis is installed, a number of optional components are available to support a variety of specialized tasks. For details, see Part III, <>. ***************************************************************** [[XI]] I. Scripted Installation ------------------------ This installation method is intended to simplify the most common situation in which isis is being installed for use as a spectral analysis tool with support for using the XSPEC spectral model library. *For The Impatient:* assuming certain requirements are met, the following steps should be sufficient to install isis into directory 'DIR': .......................................................... wget http://space.mit.edu/cxc/isis/install-isis.sh setenv HEADAS /usr/local/headas/x86_64-unknown-linux-gnu-libc2.7/ sh install-isis.sh DIR .......................................................... If reading instructions just isn't for you, then by all means go ahead and try that now, substituting the +HEADAS+ path appropriate for your system. The next section explains the process and requirements in a little more detail. Requirements ~~~~~~~~~~~~ Before running the installation script, the following programs must be available on your system: - +wget+ - +tar+ - +make+ - C compiler (eg. +gcc+) - Fortran compiler (eg. +gfortran+) See below for <> on choosing C and Fortran compilers. To verify that each of these programs is available on your command search path, use +which+: ................ > which wget /usr/bin/wget ................ The simplest way to obtain the XSPEC spectral model library is to install XSPEC itself. Isis also uses the +cfitsio+ and +pgplot+ libraries that come with XSPEC. For these reasons, the isis installation script assumes that XSPEC has been installed on your system; XSPEC is available from: + http://heasarc.gsfc.nasa.gov/docs/software/lheasoft/ When installing XSPEC, we strongly recommend compiling it from source code. Installation ~~~~~~~~~~~~ Once the above requirements are satisfied, isis installation can proceed as follows: . Move to a working directory where you have at least 200 MB of space to download and compile the software, then download the isis installation script into that directory: + ..................................................................... cd isis-src wget http://space.mit.edu/cxc/isis/install-isis.sh ..................................................................... . Set the +HEADAS+ environment variable to provide the path to your XSPEC installation. To set it, (t)csh users should type something like: + ..................................................................... setenv HEADAS /usr/local/headas/x86_64-unknown-linux-gnu-libc2.7/ ..................................................................... + while users of bash, ksh, etc.. should type something like + ......................................................... HEADAS=/usr/local/headas/x86_64-unknown-linux-gnu-libc2.7/ export HEADAS ......................................................... . Set any compiler environment variables 'CC', 'CFLAGS', 'FC', 'FFLAGS', and 'LDFLAGS' necessary to properly define your build environment (*<>*). . Run the installation script to install everything into directory 'DIR' + .......................... sh install-isis.sh DIR .......................... + If no directory 'DIR' is provided on the script command line, then everything will be installed into the current directory. If all goes well, the script will download, compile and install isis along with a few commonly used modules. When the script finishes, it will provide the path to the isis executable, e.g. 'DIR/bin/isis'. When you run isis, you should see something like this: ............................................................ > DIR/bin/isis Welcome to ISIS Version 1.6.2 Copyright (C) 1998-2012 Massachusetts Institute of Technology Isis web page: http://space.mit.edu/cxc/isis/ Mailing list archive: http://space.mit.edu/cxc/isis/archive/ Send questions to the mailing list: . For a summary of recent changes, type: "help changes" isis> ............................................................ To run isis by typing 'isis' at the unix command prompt instead of 'DIR/bin/isis', consider adding the 'DIR/bin' directory to your command search path. Alternatively, you might consider putting an appropriate symbolic link into a bin directory that's already on your path. For example, if '$HOME/bin' is on your command search path, consider putting a symbolic link there: ..................................... ln -s DIR/bin/isis $HOME/bin/isis ..................................... Now that isis is working, you may want to consider installing some of the optional software mentioned in <>. [[XII]] II. Manual Installation ----------------------- The manual installation method is available for those who want more control over the installation process. Requirements ------------ ======================================================================= The S-Lang library is required (version 2.2.4 or newer). This library is available from: + http://www.jedsoft.org/slang/ To build isis with support for fitting XSPEC spectral models, the XSPEC spectral model library must be installed somewhere on your system. This library is part of HEASoft, which is available from: + http://heasarc.gsfc.nasa.gov/docs/software/lheasoft/ Along with the spectral model library, the HEASoft installation also provides the cfitsio and pgplot libraries; if you choose not to install HEASoft, then cfitsio and pgplot must be installed. ======================================================================= Table of Contents ----------------- . <> a. <> b. <> c. <> d. <> e. <> . <> - <> - <> - <> . <> [[X1]] 1. Installing from source code ------------------------------- [[Xa]] a. Choosing compilers ~~~~~~~~~~~~~~~~~~~~ It is important to build isis and S-Lang using the same C and Fortran compilers that were used to build XSPEC. For this reason, the HEASoft compiler recommendations also apply to isis. For details, see: http://heasarc.gsfc.nasa.gov/docs/software/lheasoft/supported_platforms.html http://heasarc.gsfc.nasa.gov/docs/software/lheasoft/install.html Ideally, your C and Fortran compilers should be part of a matched set and their version numbers should match exactly. For example, using the C compiler 'gcc' and the Fortran compiler 'gfortran', one can check the version numbers like so: ................................................................. > gcc --version gcc (Debian 4.3.2-1.1) 4.3.2 > gfortran --version GNU Fortran (Debian 4.3.2-1.1) 4.3.2 ................................................................. The compilers shown in this example are likely to be compatible because they have the same version number and because they came from the same Linux distribution (Debian). To specify which compilers to use when building isis, set the +CC+ and +FC+ environment variables. For example, to set these environment variables, (t)csh users should type: ................................................................. setenv CC gcc-4.3 setenv FC gfortran-4.3 ................................................................. while bash, ksh, etc. users should type: ................................................................. CC=gcc-4.3 export CC FC=gfortran-4.3 export FC ................................................................. [[Xb]] b. Recommended installation method ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ [IMPORTANT] ================================================================= Be sure to build isis and S-Lang using the same C and Fortran compilers that were used to build XSPEC. If your compilers are incompatible, the build may fail. ================================================================= If S-Lang has been installed in a standard location such as '/usr/local', the isis installation process may be as simple as: ................................................................. ./configure --with-headas=$HEADAS make make check make install ................................................................. The +HEADAS+ environment variable gives the path to your local HEASoft installation. To set it, (t)csh users should type something like: ................................................................. setenv HEADAS /usr/local/headas/x86_64-unknown-linux-gnu-libc2.7/ ................................................................. while users of bash, ksh, etc.. should type something like: ................................................................. HEADAS=/usr/local/headas/x86_64-unknown-linux-gnu-libc2.7/ export HEADAS ................................................................. Note that the exact directory path depends on the details of your system. By default, isis files will be installed in '/usr/local/isis' and a symbolic link to the isis executable will be placed in '/usr/local/bin/isis'. If '/usr/local/bin' is already in your command search path then, after isis is installed, you should be able to run it by typing 'isis' at the unix prompt: ................................................................. > isis ................................................................. To install isis in 'DIR' instead of '/usr/local', include the '--prefix' configure option: ................................................................. --prefix=DIR ................................................................. If S-Lang has been installed in a non-standard location it may be necessary to specify its location using the '--with-slang' configure option: ................................................................. --with-slang=DIR ................................................................. To make use of the APED spectroscopy database, include the '--with-atomdb' configure option: ................................................................. --with-atomdb=DIR ................................................................. [[Xc]] c. INSTALLATION EXAMPLE ~~~~~~~~~~~~~~~~~~~~~~~ To step through a complete installation example, suppose that your compilers are in '/usr/local/bin', you want to unpack the source code in '/soft/src', and you want to install everything in '/soft', with HEASoft in '/soft/headas' and isis in '/soft/isis'. To create this setup, perform the following steps: [NOTE] ================================================================= To make this example concrete, specific software version numbers appear in the relevant URLs and command-lines. When performing a new installation, it is usually best to choose the newest available version of each package. ================================================================= . Create the /soft/src directory: + ....................... mkdir -p /soft/src ....................... + ***************************************************************** Note that creating this directory requires root permission. However, it is unwise to compile software as root. Only the last step (make install) should be performed as root. If you do not have root permission and cannot create the '/soft/src' directory, that's ok, just choose a directory where you have write permission and enough space to hold all the files. The disk space requirement is determined primarily by the size of HEASoft; S-Lang and ISIS require very little space in comparison. ***************************************************************** . Download S-Lang, isis, and HEASoft: + S-Lang source code is available from: + ftp://space.mit.edu/pub/davis/slang/v2.2/ + ISIS source code is available from: + ftp://space.mit.edu/pub/cxc/isis/ + HEASoft source code is available from: + http://heasarc.gsfc.nasa.gov/lheasoft/download.html + After downloading the source code tar files, move the files to '/soft/src': + ................................................................. mv slang-2.2.4.tar.gz /soft/src mv isis-1.6.2.tar.gz /soft/src mv heasoft-6.11.1.tar.gz /soft/src ................................................................. . Specify compilers: + In C shell variants, such as csh, tcsh, type: + ................................................................. setenv CC /usr/local/bin/gcc setenv FC /usr/local/bin/gfortran setenv CXX /usr/local/bin/g++ ................................................................. + In Bourne shell variants, such as bash, ksh, etc. type: + ................................................................. CC=/usr/local/bin/gcc export CC FC=/usr/local/bin/gfortran export FC CXX=/usr/local/bin/g++ export CXX ................................................................. . Install S-Lang: + ................................................................. cd /soft/src gunzip -c slang-2.2.4.tar.gz | tar xf - cd slang-2.2.4 ./configure --prefix=/soft make make install ................................................................. . Install HEASoft: + ................................................................. cd /soft/src ................................................................. + Follow the installation instructions in + http://heasarc.gsfc.nasa.gov/docs/software/lheasoft/install.html + ***************************************************************** Be sure to run the HEASoft configure script with the appropriate '--prefix' option so that HEASoft will be installed in the directory chosen for this example, '/soft/src/headas': ................................................................. ./configure --prefix=/soft/src/headas ... ................................................................. Once HEASoft is installed, the HEADAS environment variable should be set to ................................................................. /soft/src/headas// ................................................................. as shown above. ***************************************************************** . Install isis: + ................................................................. cd /soft/src gunzip -c isis-1.6.2.tar.gz | tar xf - cd isis-1.6.2 ./configure --prefix=/soft --with-slang=/soft \ --with-headas=$HEADAS make make check make install ................................................................. At this point, '/soft/bin/isis' should be a symbolic link to the isis executable. When you run it, you should see something like this: ................................................................. > /soft/bin/isis Welcome to ISIS Version 1.6.2 Copyright (C) 1998-2012 Massachusetts Institute of Technology Isis web page: http://space.mit.edu/cxc/isis/ Mailing list archive: http://space.mit.edu/cxc/isis/archive/ Send questions to the mailing list: . For a summary of recent changes, type: "help changes" isis> ................................................................. Once isis is working, you may want to consider installing some of the optional software mentioned in <>. For a complete list of supported configure options, do: .................................. ./configure --help .................................. Many of these configure options are described in the next section. [[Xd]] [glossary] d. Configure options ~~~~~~~~~~~~~~~~~~~~ --with-prefix=DIR:: Use this option to install isis files in 'DIR/isis/$version'. --with-subdir=DIR:: Use this option to install isis files in '$prefix/isis/DIR' instead of '$prefix/isis/$version'. If DIR="" (the empty string) then isis files will be installed in '$prefix/isis'. --with-headas=$HEADAS:: Use this option to provide the path to the xspec libraries. When the cfitsio and pgplot libraries are present in '$HEADAS/lib', it is usually best to use them when building isis, rather than any other versions of these libraries that may be available on your system. For this reason, it is usually best to avoid combining the --with-headas option with any of the --with-cfitsio or --with-pgplot options. --with-atomdb=$ATOMDB:: Use this option to provide the path to the ATOMDB spectroscopy database, available from: http://www.atomdb.org/ --with-xspec-version=nn:: When your local HEASoft installation includes both xspec11 and xspec12, use this option to specify which version of the xspec libraries to link to isis. If this configure option is absent, and both xspec versions are present, isis will use xspec12. --with-xspec-static:: Use this option to indicate that the xspec libraries should be statically linked to the isis executable. --with-xspec-modelsonly=DIR:: Use this option to provide the path to your xspec modelsonly library installation. When this option is used, the CCfits library must also be installed on your system. The location of the CCfits library should be specified unless the library is installed in'$prefix' or another standard location. --with-local-setup=FILE:: Use this option to indicate that the S-Lang script in FILE should be loaded when isis starts up. This file can be used to define site-local customizations that may be helpful for all users at your site. --with-slang=DIR:: Use this option to indicate that libslang is in 'DIR/lib' and slang.h is in 'DIR/include' --with-slanglib=LIB_DIR:: --with-slanginc=INC_DIR:: Use these options to indicate that libslang is in 'LIB_DIR' and slang.h is in 'INC_DIR'. If you use these options, do not use the --with-slang option. --with-cfitsio=DIR:: Use this option to indicate that libcfitsio is in 'DIR/lib' and fitsio.h is in 'DIR/include'. --with-cfitsiolib=LIB_DIR:: --with-cfitsioinc=INC_DIR:: Use these options to indicate that libcfitsio is in 'LIB_DIR' and fitsio.h is in 'INC_DIR'. If you use these options, do not use the --with-cfitsio option. --with-pgplot=DIR:: Use this option to indicate that libpgplot is in 'DIR/lib' and cpgplot.h is in 'DIR/include' --with-pgplotlib=LIB_DIR:: --with-pgplotinc=INC_DIR:: Use these options to indicate that libpgplot is in 'LIB_DIR' and cpgplot.h is in 'INC_DIR'. If you use these options, do not use the --with-pgplot option. --with-CCfits=DIR:: Use this option to indicate that libCCfits is in 'DIR/lib' and CCfits.h is in 'DIR/include' --with-CCfitslib=LIB_DIR:: --with-CCfitsinc=INC_DIR:: Use these options to indicate that libCCfits is in 'LIB_DIR' and CCfits.h is in 'INC_DIR'. If you use these options, do not use the --with-CCfits option. --with-dep=DIR:: Use this option to indicate that slang and cfitsio are installed in 'DIR/lib' and 'DIR/include', and that pgplot is installed in 'DIR/pgplot'. --with-readline[=arg]:: Use this option to select which readline library to use: - arg=gnu means use GNU readline - arg=DIR means use GNU readline (from 'DIR/lib' and 'DIR/include') - arg=slang means use S-Lang readline only --with-fclibs="...":: Use this option to provide additional libraries that may be needed by your compilers, but that are not automatically picked up by the configure script. For example, if you choose to compile isis with a C\+\+ compiler (not recommended), you may need to use --with-fclibs="-lstdc++". --x-libraries=DIR/lib:: --x-includes=DIR/include:: Use these options to indicate that the X libraries and include files are installed in 'DIR/lib' and 'DIR/include', respectively. [[Xe]] e. (optional) Installing modules ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ You may wish to install additional isis- or slang-related software, such as one or more of the modules available from + http://space.mit.edu/cxc/isis/modules.html. Such modules should be installed in the same directory tree where you installed slang, so that S-Lang applications such as isis will automatically find the new modules. For example, consider adding the histogram module to the installation described above, where both isis and slang were installed in /soft. To install the histogram module, do the following: First, download the module source code tar file from + http://space.mit.edu/CXC/software/slang/modules/hist/src/ Then, assuming the tar file is in /soft/src, do: ................................................................. cd /soft/src gunzip -c slhist-0.3.2a.tar.gz | tar xf - cd slhist-0.3.2a ./configure --prefix=/soft --with-slang=/soft make make install ................................................................. The histogram module can then be imported into isis like so: ................................................................. isis> require ("histogram"); ................................................................. If you install a module that depends on other libraries (e.g. libpvm), then those additional libraries may be installed either in a standard system location (e.g. /usr) or in the same directory tree as isis (e.g. /soft), depending on which is most convenient. [[X2]] 2. Installation suggestions for specific architectures ------------------------------------------------------- [[Xlinux]] Linux systems: ~~~~~~~~~~~~~ - Recommended compilers: use gcc-4.3 and gfortran-4.3, or newer. + Older compilers will also work, but code compiled by older versions of gfortran is not fully compatible with newer versions of gfortran. On older systems, using gcc-3.4 with g77 will work; note, however, that g77 is no longer maintained. [[Xmac]] Mac OS X systems: ~~~~~~~~~~~~~~~~ - See http://space.mit.edu/cxc/isis/mac_install.html [[Xsolaris]] Solaris systems: ~~~~~~~~~~~~~~~ - The Solaris compilers are preferred: CC=cc and FC=f90 AIX systems: ~~~~~~~~~~~ - The IBM compilers are preferred: CC=xlc and FC=xlf [[X3]] 3. TROUBLESHOOTING ------------------ Answers to some frequently asked questions are available from the web site: + http://space.mit.edu/cxc/isis/faq.html If isis did not compile: ~~~~~~~~~~~~~~~~~~~~~~~~ - Did you build isis <> that were used to build the XSPEC libraries? - Are your C and Fortran compilers <>? [[XIII]] III. Optional Components ------------------------ ======================================================================= Isis provides extensive support for constructing multi-component collisional ionization equilibrium spectral models using the ATOMDB spectroscopy database, available from: + http://www.atomdb.org/ A growing collection of modules and data analysis packages is available from: + http://space.mit.edu/cxc/isis/modules.html The available data analysis packages provide support for timing analysis, automated processing of Chandra grating data, and analysis of density-dependent line ratios from He-like triplet lines. The available modules provide support for low-level I/O of FITS and HDF5 files, interaction with the ds9 image viewer, an interface to the GSL scientific library, 3D visualization, PVM-based parallel processing, and more. ======================================================================= Appendix -------- *********************************************************************** Below, I have attached the generic INSTALL instructions included in the autoconf distribution. These instructions provide more detail on how the configure script works and also describe other installation options which may be supported by the configure script. *********************************************************************** Copyright (C) 1994, 1995, 1996, 1999, 2000, 2001, 2002 Free Software Foundation, Inc. This file is free documentation; the Free Software Foundation gives unlimited permission to copy, distribute and modify it. Basic Installation ------------------ These are generic installation instructions. The 'configure' shell script attempts to guess correct values for various system-dependent variables used during compilation. It uses those values to create a 'Makefile' in each directory of the package. It may also create one or more '.h' files containing system-dependent definitions. Finally, it creates a shell script 'config.status' that you can run in the future to recreate the current configuration, and a file 'config.log' containing compiler output (useful mainly for debugging 'configure'). It can also use an optional file (typically called 'config.cache' and enabled with '--cache-file=config.cache' or simply '-C') that saves the results of its tests to speed up reconfiguring. (Caching is disabled by default to prevent problems with accidental use of stale cache files.) If you need to do unusual things to compile the package, please try to figure out how 'configure' could check whether to do them, and mail diffs or instructions to the address given in the 'README' so they can be considered for the next release. If you are using the cache, and at some point 'config.cache' contains results you don't want to keep, you may remove or edit it. The file 'configure.ac' (or 'configure.in') is used to create 'configure' by a program called 'autoconf'. You only need 'configure.ac' if you want to change it or regenerate 'configure' using a newer version of 'autoconf'. The simplest way to compile this package is: . 'cd' to the directory containing the package's source code and type './configure' to configure the package for your system. If you're using 'csh' on an old version of System V, you might need to type 'sh ./configure' instead to prevent 'csh' from trying to execute 'configure' itself. + Running 'configure' takes awhile. While running, it prints some messages telling which features it is checking for. . Type 'make' to compile the package. . Optionally, type 'make check' to run any self-tests that come with the package. . Type 'make install' to install the programs and any data files and documentation. . You can remove the program binaries and object files from the source code directory by typing 'make clean'. To also remove the files that 'configure' created (so you can compile the package for a different kind of computer), type 'make distclean'. There is also a 'make maintainer-clean' target, but that is intended mainly for the package's developers. If you use it, you may have to get all sorts of other programs in order to regenerate files that came with the distribution. Compilers and Options --------------------- Some systems require unusual options for compilation or linking that the 'configure' script does not know about. Run './configure --help' for details on some of the pertinent environment variables. You can give 'configure' initial values for configuration parameters by setting variables in the command line or in the environment. Here is an example: .................................................... ./configure CC=c89 CFLAGS=-O2 LIBS=-lposix ................................................... See <>, for more details. Compiling For Multiple Architectures ------------------------------------ You can compile the package for more than one kind of computer at the same time, by placing the object files for each architecture in their own directory. To do this, you must use a version of 'make' that supports the 'VPATH' variable, such as GNU 'make'. 'cd' to the directory where you want the object files and executables to go and run the 'configure' script. 'configure' automatically checks for the source code in the directory that 'configure' is in and in '..'. If you have to use a 'make' that does not support the 'VPATH' variable, you have to compile the package for one architecture at a time in the source code directory. After you have installed the package for one architecture, use 'make distclean' before reconfiguring for another architecture. Installation Names ------------------ By default, 'make install' will install the package's files in '/usr/local/bin', '/usr/local/man', etc. You can specify an installation prefix other than '/usr/local' by giving 'configure' the option '--prefix=PATH'. You can specify separate installation prefixes for architecture-specific files and architecture-independent files. If you give 'configure' the option '--exec-prefix=PATH', the package will use PATH as the prefix for installing programs and libraries. Documentation and other data files will still use the regular prefix. In addition, if you use an unusual directory layout you can give options like '--bindir=PATH' to specify different values for particular kinds of files. Run 'configure --help' for a list of the directories you can set and what kinds of files go in them. If the package supports it, you can cause programs to be installed with an extra prefix or suffix on their names by giving 'configure' the option '--program-prefix=PREFIX' or '--program-suffix=SUFFIX'. Optional Features ----------------- Some packages pay attention to '--enable-FEATURE' options to 'configure', where FEATURE indicates an optional part of the package. They may also pay attention to '--with-PACKAGE' options, where PACKAGE is something like 'gnu-as' or 'x' (for the X Window System). The 'README' should mention any '--enable-' and '--with-' options that the package recognizes. For packages that use the X Window System, 'configure' can usually find the X include and library files automatically, but if it doesn't, you can use the 'configure' options '--x-includes=DIR' and '--x-libraries=DIR' to specify their locations. Specifying the System Type -------------------------- There may be some features 'configure' cannot figure out automatically, but needs to determine by the type of machine the package will run on. Usually, assuming the package is built to be run on the _same_ architectures, 'configure' can figure that out, but if it prints a message saying it cannot guess the machine type, give it the '--build=TYPE' option. TYPE can either be a short name for the system type, such as 'sun4', or a canonical name which has the form: ............................ CPU-COMPANY-SYSTEM ............................ where SYSTEM can have one of these forms: ............................ OS KERNEL-OS ............................ See the file 'config.sub' for the possible values of each field. If 'config.sub' isn't included in this package, then this package doesn't need to know the machine type. If you are _building_ compiler tools for cross-compiling, you should use the '--target=TYPE' option to select the type of system they will produce code for. If you want to _use_ a cross compiler, that generates code for a platform different from the build platform, you should specify the "host" platform (i.e., that on which the generated programs will eventually be run) with '--host=TYPE'. Sharing Defaults ---------------- If you want to set default values for 'configure' scripts to share, you can create a site shell script called 'config.site' that gives default values for variables like 'CC', 'cache_file', and 'prefix'. 'configure' looks for 'PREFIX/share/config.site' if it exists, then 'PREFIX/etc/config.site' if it exists. Or, you can set the 'CONFIG_SITE' environment variable to the location of the site script. A warning: not all 'configure' scripts look for a site script. [[X7]] Defining Variables ------------------ Variables not defined in a site shell script can be set in the environment passed to 'configure'. However, some packages may run configure again during the build, and the customized values of these variables may be lost. In order to avoid this problem, you should set them in the 'configure' command line, using 'VAR=value'. For example: ................................... ./configure CC=/usr/local2/bin/gcc ................................... will cause the specified gcc to be used as the C compiler (unless it is overridden in the site shell script). 'configure' Invocation ---------------------- 'configure' recognizes the following options to control how it operates. '--help':: '-h':: Print a summary of the options to 'configure', and exit. '--version':: '-V':: Print the version of Autoconf used to generate the 'configure' script, and exit. '--cache-file=FILE':: Enable the cache: use and save the results of the tests in FILE, traditionally 'config.cache'. FILE defaults to '/dev/null' to disable caching. '--config-cache':: '-C':: Alias for '--cache-file=config.cache'. '--quiet':: '--silent':: '-q':: Do not print messages saying which checks are being made. To suppress all normal output, redirect it to '/dev/null' (any error messages will still be shown). '--srcdir=DIR':: Look for the package's source code in directory DIR. Usually 'configure' can determine that directory automatically. 'configure' also accepts some other, not widely useful, options. Run 'configure --help' for more details.