NAME
mpif77 - Compile LAM FORTRAN programs.
SYNTAX
mpif77 [-showme|-showme:compile|-showme:link] ...
OPTIONS
-showme
Does not invoke the underlying FORTRAN compiler. Instead, it
shows the full command line that would be executed to compile
the FORTRAN program.
-showme:compile
Does not invoke the underlying FORTRAN compiler. Instead, it
shows the compiler flags that would be supplied to the FORTRAN
compiler.
-showme:link
Does not invoke the underlying FORTRAN compiler. Instead, it
shows the linker flags that would be supplied to the FORTRAN
compiler.
See f77(1) (or whatever your underlying FORTRAN compiler is) for all
other options.
DESCRIPTION
mpif77 is a convenience wrapper for the local native FORTRAN compiler.
Translation of a LAM program requires the linkage of the LAM essential
services libraries which may not reside in one of the standard search
directories of ld(1). mpif77 passes its arguments along to the local
native FORTRAN compiler along with the -L and -l options required by
LAM/MPI programs. This includes all necessary options for ROMIO and/or
C++ bindings support (if ROMIO/C++ support was included when LAM was
compiled).
The LAM Team strongly encourages using mpif77 instead of attempting to
link to the LAM libraries manually. This allows the specific
implementation of LAM to change without forcing changes to linker
directives in users' Makefiles (the specific set of underlying LAM
libraries has already changed multiple times, and will likely change
again in future versions).
Indeed, since mpif77 is a very thin wrapper on top of an underlying
compiler, there are very, very few compelling reasons not to use
mpif77. When it is not possible to use mpif77, the -showme:compile and
-showme:link arguments should be used instead. For example:
shell$ f77 -c file1.f `mpif77 -showme:compile`
shell$ f77 -c file2.f `mpif77 -showme:compile`
shell$ f77 file1.o file2.o `mpif77 -showme:link` -o my_mpi_program
ENVIRONMENT VARIABLES
By default, mpif77 uses the FORTRAN compiler that was selected when LAM
was configured (with the --with-fc flag to ./configure) as the local
native FORTRAN compiler, but this can be overridden by the LAMMPIF77
environment variable (an older name for this environment variable is
LAMHF77 -- this also still works, but its use is deprecated).
If the environment variable LAMHOME is set, mpif77 will use its value
as the location of the LAM installation directory instead of the value
that was compiled into mpif77. This means that mpif77 will use the
value of LAMHOME as the base to create the -I and -L arguments that are
passed to the lower-level compiler, not the installation directory that
was supplied when mpif77 was created. This is almost always a Bad
Idea.
The use of LAMHOME is discouraged except for some rare configuration
cases in oddly networked sites (in which case your system administrator
should probably set this up), and for advanced users with multiple
LAM/MPI installations who really know what they are doing; if the
LAMHOME environment variable is unintentionally left set, it can lead
to tremendous user confusion. For example, if LAMHOME points to LAM
installation A, but the user's PATH points to LAM installation B, then
even though B's mpif77 will be used, the user program will be compiled
and linked against LAM installation A.
The LAMHOME environment variable is mainly only left in place for
backwards compatibility; it is not required for normal functioning of
LAM/MPI. The LAM Team discourages the use of the LAMHOME environment
variable, and instead advocates simply setting the PATH properly to
switch between multiple LAM/MPI implementations.
NOTES
Previous versions of LAM encouraged the use of hf77 to compile LAM
and/or MPI Fortran applications. In very old versions of LAM, hf77 did
not automatically add -lmpi to the command line. hf77 was eventually
deprecated and replaced with mpif77. The executable hf77 is now simply
a symbolic link to mpif77 just in case there's anyone out there that
still uses that name. It should be harmless to pass in the additional
-lmpi; mpif77 should silently do the Right Thing (only link in the MPI
library once).
SEE ALSO
f77(1), ld(1), lam-helpfile(5), mpicc(1)