HP Fortran Programmer's Guide (B3908-90031; September 2011)

Compiling and linking
Using environment variables
Chapter 2 97
Using environment variables
Environment variables are variables that are defined in the operating environment of the system and are
available to various system components. For example, when you run a program, the shell looks at the PATH
variable to determine where the program is located. Table 2-15 lists and briefly describes the environment
variables that control the way HP Fortran programs are compiled, linked, and run.
The following sections describe how to use the HP_F90_OPTS, LPATH, and MP_NUMBER_OF_THREADS
environment variables. See the environ(5) man page for information about system-level environment
variables.
HP_F90OPTS environment variable
The HP_F90OPTS environment variable is read by the f90 driver for options to insert in the command line.
This variable is useful when you want the same options and arguments each time you invoke the f90
command. For example, if HP_F90OPTS is set to the -v option, the following command line:
$ f90 +list hello.f90
is equivalent to:
$ f90 -v +list hello.f90
Table 2-15 HP Fortran environment variables
Environment variable Description
ST_F90COM[64] Specifies the path of 32-bit or 64-bit f90 compiler respectively in case
of alternate root installation.
HP_F90OPTS Specifies a list of command-line options that f90 inserts in the
command line that invokes the HP Fortran compiler.
LPATH Specifies a list of directories that the linker is to search for libraries.
MP_NUMBER_OF_THREADS Specifies the desired number of processors to be used to run
HP Fortran programs that have been compiled for parallel execution.
TMPDIR Specifies a directory for temporary files; used in place of the default
directory /var/tmp.
TTYUNBUF Controls tty buffering. To enable tty buffering, set TTYUNBUF to 0; to
disable tty buffering, set it to a nonzero value.