---
name: "mpif77.lam"
section: "1"
platform: "linux"
package: "lam4-dev"
version: "7.1.4-7.2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/mpif77.lam"
---

# mpif77.lam(1)

Compile LAM FORTRAN programs.

## NAME

mpif77 - Compile LAM FORTRAN programs.

## SYNOPSIS

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)](/f77/1.md) (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)](/ld/1.md). *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)](/f77/1.md), [ld(1)](/ld/1.md), [lam-helpfile(5)](/lam-helpfile/5.md), [mpicc(1)](/mpicc/1.md)