.TH mpicxx 1 "11/12/2019" " " "MPI"

.SH NAME

mpicxx \-  Compiles and links MPI programs written in C++ 

.SH DESCRIPTION

This command can be used to compile and link MPI programs written in

C++.  It provides the options and any special libraries that are

needed to compile and link MPI programs.

It is important to use this command, particularly when linking programs,

as it provides the necessary libraries.

.SH COMMAND LINE ARGUMENTS

.PD 0

.TP

.B -show      

- Show the commands that would be used without

running them

.PD 1

.PD 0

.TP

.B -help      

- Give short help

.PD 1

.PD 0

.TP

.B -cxx=name   

- Use compiler 

.I name

instead of the default choice.  Use

this only if the compiler is compatible with the MPICH

library (see below)

.PD 1

.PD 0

.TP

.B -config=name 

- Load a configuration file for a particular compiler.

This allows a single 

.I mpicxx

command to be used with 

multiple compilers.

.PD 1

.PD 0

.TP

.B -compile_info 

- Show the steps for compiling a program.  This option

can be used to see what options and include paths are

used by mpicxx.

.PD 1

.PD 0

.TP

.B -link_info 

- Show the steps for linking a program.  This option

can be used to see what options and libraries are used by

mpicxx.

.PD 1

.PD 0

.TP

.B -profile=name 

- Use the MPI profiling given by name.  See below for

details

.PD 1

.PD 0

.TP

.B -echo      

- Show exactly what this program is doing.

This option should normally not be used.

.PD 1

.PD 0

.TP

.B -static

- mpi - Use a statically compile MPI library, but shared libraries

for all of the other dependencies.

.PD 1

.PD 0

.TP

.B others     

- are passed to the compiler or linker.  For example, 

.I \\-c

causes files to be compiled, 

.I \\-g

selects compilation with

debugging on most systems, and 

.I \\-o name

causes linking

with the output executable given the name 

.I name

\&.

.PD 1

.SH ENVIRONMENT VARIABLES

The environment variables 

.I MPICH_CXX

may be used

to select different C++ compiler and linker.  Note that since

MPICH is built with a particular C and Fortran compiler, changing the

compilers used can cause problems.  Use this only if you could intermix

code compiled with the different compilers.

The environment variable 

.I MPICC_PROFILE

specifies a profile library

and has the same effect as if 

.I \\-profile=$MPICC_PROFILE

were used as

an argument to 

.I mpicc

\&.

See the discussion of 

.I \\-profile

below for more

details.

.SH COMPATIBLE COMPILERS

The MPI library may be used with any compiler that uses the same

lengths for basic data objects (such as 

.I long double

) and that

uses compatible run-time libraries.  On many systems, the various

compilers are compatible and may be used interchangably.  There are

exceptions; if you use the 

.I MPICH_CXX

environment variable or the

.I \\-cxx=name

command-line argument to override the choice of compiler

and encounter problems, try reconfiguring MPICH with the new compiler,

and installing MPICH in a separate location.  See the installation manual

for more details.

.SH EXAMPLES

To compile a single file 

.I foo.c

, use

.nf

mpicxx -c foo.cxx

.fi

To link the output and make an executable, use

.nf

mpicxx -o foo foo.o

.fi

Combining compilation and linking in a single command

.nf

mpicxx -o foo foo.cxx

.fi

is a convenient way to build simple programs.

.SH SELECTING A PROFILING LIBRARY

The 

.I \\-profile=name

argument allows you to specify an MPI profiling

library to be used.  

.I name

can have two forms:

.br

A library in the same directory as the MPI library

.br

The name of a profile configuration file

.br

If 

.I name

is a library, then this library is included before the MPI

library.  This allows the simple use of libraries that make use of the

MPI profiling interface and that are installed in the same directory as

the MPI library.

If 

.I name.conf

is the name of a file in the sysconfdir directory, then this

is read and may define the following variables:

.PD 0

.TP

.B PROFILE_PRELIB 

- Libraries (and paths) to include before the MPI library

.PD 1

.PD 0

.TP

.B PROFILE_POSTLIB 

- Libraries to include after the MPI library

.PD 1

.PD 0

.TP

.B PROFILE_INCPATHS 

- C preprocessor arguments for any include files

For example, to add 

.I /usr/local/myprof/include

to the include path and

the library 

.I libmyprof.a

in 

.I /usr/local/myprof/lib

to the link step, 

you could create the file 

.I myprof.conf

with the lines

.PD 1

.nf

PROFILE_PRELIB="-L/usr/local/myprof/lib -lmyprof"

PROFILE_INCPATHS="-I/usr/local/myprof/include"

.fi

and place it in the sysconfdir directory (this directory is set at

configure time when MPICH is built).  Then using the command-line

argument 

.I \\-profile=myprof

will cause these

definitions to be added to the relevant compile commands.

.SH SEE ALSO

mpicc, mpifort, mpiexec

.br