NERSC GNU Tools

• GNU module
• GNU.tools module
• gcc module
• using CVS
• Online information
• Source Availability

NERSC provides several of the GNU tools for the convenience of its users. Support for these tools is limited and NERSC can not guarantee that they will perform as advertised. The user assumes any risks in using these tools. The executables may be updated at any time without notice. To see the current version of any GNU tool just run the tool with the --version option.

GNU module

These tools are only accessible via the modules environment. To use these tools load the GNU module. This is done either interactively or in your .login or .profile by performing the following command:

% module add GNU

Once the module is installed then any GNU command will be used preferentially over any operating system command of the same name. If in doubt as to which command is being executed type

csh:

which command

sh or ksh:

type command

GNU.tools module

If you don't want to mask the operating system commands then load the GNU.tools module instead.

% module add GNU.tools

Those GNU commands that would mask the equivalent operating system command will have a prepended ``g'' to identify them and to make them unique. For example, The GNU ls would only be available as gls. This is also done in the GNU module for convenience where both ls and gls would access the GNU version.

GNU Compilers

The gcc, g++, and g77 compilers are provided by the gcc module. These programs can be accessed by typing,

% module load gcc

This suite of compilers is not particularly well tuned for high performance optimizations on the POWER architecture, but does provide for easy compilation of many freely available portable utilities. These compilers are also useful in debugging production codes via comparison of the results from different compilers.

The GNU compilers include the -Wall flag which provides useful feedback about portability and language specification compliance.

POE parallel programs can be created by including the -mpe flag when compiling and linking.

32 bit mode is the default. 64 bit mode is avliable via the -maix64 compiler flag.

Online information

Many of the GNU utilities do not have man pages. GNU eschews man pages in favor of its info utility and some emacs direct connection. Anyone using GNU tools can expect that the --help option will give enhanced usage information also. Users can get further help, for example, for the m4 preprocessor with either: m4 --help or info --file m4 given in order from least to most information content.

Source Availability

The sources are freely available under the GNU ``copyleft''.

The sources are in gzip'd tar files in the $GNUROOT/src directory. Some modifications may have been made to allow the sources to compile on the NERSC platforms. Look at the README file for details. The original sources are available by anonymous ftp from ftp://ftp.gnu.org/gnu/, the GNU home.