FORT77(1)                  POSIX Programmer's Manual                 FORT77(1)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.

NAME
       fort77 -- FORTRAN compiler (FORTRAN)

SYNOPSIS
       fort77 [[-c]] [[-g]] [[-L directory]]... [[-O optlevel]] [[-o outfile]] [[-s]]
           [[-w]] operand...

DESCRIPTION
       The fort77 utility is the interface to the FORTRAN compilation system;
       it shall accept the full FORTRAN-77 language defined by the
       ANSI X3.9-1978 standard. The system conceptually consists of a compiler
       and link editor. The files referenced by operands are compiled and
       linked to produce an executable file. It is unspecified whether the
       linking occurs entirely within the operation of fort77; some
       implementations may produce objects that are not fully resolved until
       the file is executed.

       If the -c option is present, for all pathname operands of the form
       file..ff, the files:


           $(basename pathname.f).o

       shall be created or overwritten as the result of successful
       compilation. If the -c option is not specified, it is unspecified
       whether such .o files are created or deleted for the file..ff operands.

       If there are no options that prevent link editing (such as -c) and all
       operands compile and link without error, the resulting executable file
       shall be written into the file named by the -o option (if present) or
       to the file a.out.  The executable file shall be created as specified
       in the System Interfaces volume of POSIX.1-2017, except that the file
       permissions shall be set to: S_IRWXO | S_IRWXG | S_IRWXU

       and that the bits specified by the umask of the process shall be
       cleared.

OPTIONS
       The fort77 utility shall conform to the Base Definitions volume of
       POSIX.1-2017, Section 12.2, Utility Syntax Guidelines, except that:

        *  The -l library operands have the format of options, but their
           position within a list of operands affects the order in which
           libraries are searched.

        *  The order of specifying the multiple -L options is significant.

        *  Conforming applications shall specify each option separately; that
           is, grouping option letters (for example, -cg) need not be
           recognized by all implementations.

       The following options shall be supported:

       -c        Suppress the link-edit phase of the compilation, and do not
                 remove any object files that are produced.

       -g        Produce symbolic information in the object or executable
                 files; the nature of this information is unspecified, and may
                 be modified by implementation-defined interactions with other
                 options.

       -s        Produce object or executable files, or both, from which
                 symbolic and other information not required for proper
                 execution using the exec family of functions defined in the
                 System Interfaces volume of POSIX.1-2017 has been removed
                 (stripped).  If both -g and -s options are present, the
                 action taken is unspecified.

       -o outfile
                 Use the pathname outfile, instead of the default a.out, for
                 the executable file produced. If the -o option is present
                 with -c, the result is unspecified.

       -L directory
                 Change the algorithm of searching for the libraries named in
                 -l operands to look in the directory named by the directory
                 pathname before looking in the usual places. Directories
                 named in -L options shall be searched in the specified order.
                 At least ten instances of this option shall be supported in a
                 single fort77 command invocation. If a directory specified by
                 a -L option contains a file named libf.a, the results are
                 unspecified.

       -O optlevel
                 Specify the level of code optimization. If the optlevel
                 option-argument is the digit ''00'', all special code
                 optimizations shall be disabled. If it is the digit ''11'', the
                 nature of the optimization is unspecified. If the -O option
                 is omitted, the nature of the system's default optimization
                 is unspecified. It is unspecified whether code generated in
                 the presence of the -O 0 option is the same as that generated
                 when -O is omitted. Other optlevel values may be supported.

       -w        Suppress warnings.

       Multiple instances of -L options can be specified.

OPERANDS
       An operand is either in the form of a pathname or the form -l library.
       At least one operand of the pathname form shall be specified. The
       following operands shall be supported:

       file.ff    The pathname of a FORTRAN source file to be compiled and
                 optionally passed to the link editor. The filename operand
                 shall be of this form if the -c option is used.

       file.aa    A library of object files typically produced by ar, and
                 passed directly to the link editor. Implementations may
                 recognize implementation-defined suffixes other than .a as
                 denoting object file libraries.

       file.oo    An object file produced by fort77 -c and passed directly to
                 the link editor. Implementations may recognize
                 implementation-defined suffixes other than .o as denoting
                 object files.

       The processing of other files is implementation-defined.

       -l library
                 (The letter ell.) Search the library named:


                     lib_l_i_b_r_a_r_y.a

                 A library is searched when its name is encountered, so the
                 placement of a -l operand is significant. Several standard
                 libraries can be specified in this manner, as described in
                 the EXTENDED DESCRIPTION section.  Implementations may
                 recognize implementation-defined suffixes other than .a as
                 denoting libraries.

STDIN
       Not used.

INPUT FILES
       The input file shall be one of the following: a text file containing
       FORTRAN source code; an object file in the format produced by fort77
       -c; or a library of object files, in the format produced by archiving
       zero or more object files, using ar.  Implementations may supply
       additional utilities that produce files in these formats. Additional
       input files are implementation-defined.

       A <tab> encountered within the first six characters on a line of source
       code shall cause the compiler to interpret the following character as
       if it were the seventh character on the line (that is, in column 7).

ENVIRONMENT VARIABLES
       The following environment variables shall affect the execution of
       fort77:

       LANG      Provide a default value for the internationalization
                 variables that are unset or null. (See the Base Definitions
                 volume of POSIX.1-2017, Section 8.2, Internationalization
                 Variables for the precedence of internationalization
                 variables used to determine the values of locale categories.)

       LC__ALL    If set to a non-empty string value, override the values of
                 all the other internationalization variables.

       LC__CTYPE  Determine the locale for the interpretation of sequences of
                 bytes of text data as characters (for example, single-byte as
                 opposed to multi-byte characters in arguments and input
                 files).

       LC__MESSAGES
                 Determine the locale that should be used to affect the format
                 and contents of diagnostic messages written to standard
                 error.

       NLSPATH   Determine the location of message catalogs for the processing
                 of LC__MESSAGES.

       TMPDIR    Determine the pathname that should override the default
                 directory for temporary files, if any.

ASYNCHRONOUS EVENTS
       Default.

STDOUT
       Not used.

STDERR
       The standard error shall be used only for diagnostic messages.  If more
       than one file operand ending in .f (or possibly other unspecified
       suffixes) is given, for each such file:


           "%s:\n", <file>

       may be written to allow identification of the diagnostic message with
       the appropriate input file.

       This utility may produce warning messages about certain conditions that
       do not warrant returning an error (non-zero) exit value.

OUTPUT FILES
       Object files, listing files, and executable files shall be produced in
       unspecified formats.

EXTENDED DESCRIPTION
   Standard Libraries
       The fort77 utility shall recognize the following -l operand for the
       standard library:

       -l ff      This library contains all functions referenced in the
                 ANSI X3.9-1978 standard. This operand shall not be required
                 to be present to cause a search of this library.

       In the absence of options that inhibit invocation of the link editor,
       such as -c, the fort77 utility shall cause the equivalent of a -l ff
       operand to be passed to the link editor as the last -l operand, causing
       it to be searched after all other object files and libraries are
       loaded.

       It is unspecified whether the library libf.a exists as a regular file.
       The implementation may accept as -l operands names of objects that do
       not exist as regular files.

   External Symbols
       The FORTRAN compiler and link editor shall support the significance of
       external symbols up to a length of at least 31 bytes; case folding is
       permitted. The action taken upon encountering symbols exceeding the
       implementation-defined maximum symbol length is unspecified.

       The compiler and link editor shall support a minimum of 511 external
       symbols per source or object file, and a minimum of 4095 external
       symbols total. A diagnostic message is written to standard output if
       the implementation-defined limit is exceeded; other actions are
       unspecified.

EXIT STATUS
       The following exit values shall be returned:

        0    Successful compilation or link edit.

       >0    An error occurred.

CONSEQUENCES OF ERRORS
       When fort77 encounters a compilation error, it shall write a diagnostic
       to standard error and continue to compile other source code operands.
       It shall return a non-zero exit status, but it is implementation-
       defined whether an object module is created. If the link edit is
       unsuccessful, a diagnostic message shall be written to standard error,
       and fort77 shall exit with a non-zero status.

       The following sections are informative.

APPLICATION USAGE
       None.

EXAMPLES
       The following usage example compiles xyz.f and creates the executable
       file foo:


           fort77 -o foo xyz.f

       The following example compiles xyz.f and creates the object file xyz.o:


           fort77 -c xyz.f

       The following example compiles xyz.f and creates the executable file
       a.out:


           fort77 xyz.f

       The following example compiles xyz.f, links it with b.o, and creates
       the executable a.out:


           fort77 xyz.f b.o

RATIONALE
       The name of this utility was chosen as fort77 to parallel the renaming
       of the C compiler. The name f77 was not chosen to avoid problems with
       historical implementations. The ANSI X3.9-1978 standard was selected as
       a normative reference because the ISO/IEC version of FORTRAN-77 has
       been superseded by the ISO/IEC 1539:1991 standard.

       The file inclusion and symbol definition #define mechanisms used by the
       c99 utility were not included in this volume of POSIX.1-2017--even
       though they are commonly implemented--since there is no requirement
       that the FORTRAN compiler use the C preprocessor.

       The -onetrip option was not included in this volume of POSIX.1-2017,
       even though many historical compilers support it, because it is derived
       from FORTRAN-66; it is an anachronism that should not be perpetuated.

       Some implementations produce compilation listings. This aspect of
       FORTRAN has been left unspecified because there was controversy
       concerning the various methods proposed for implementing it: a -V
       option overlapped with historical vendor practice and a naming
       convention of creating files with .l suffixes collided with historical
       lex file naming practice.

       There is no -I option in this version of this volume of POSIX.1-2017 to
       specify a directory for file inclusion. An INCLUDE directive has been a
       part of the Fortran-90 discussions, but an interface supporting that
       standard is not in the current scope.

       It is noted that many FORTRAN compilers produce an object module even
       when compilation errors occur; during a subsequent compilation, the
       compiler may patch the object module rather than recompiling all the
       code. Consequently, it is left to the implementor whether or not an
       object file is created.

       A reference to MIL-STD-1753 was removed from an early proposal in
       response to a request from the POSIX FORTRAN-binding standard
       developers. It was not the intention of the standard developers to
       require certification of the FORTRAN compiler, and IEEE Std 1003.9-1992
       does not specify the military standard or any special preprocessing
       requirements. Furthermore, use of that document would have been
       inappropriate for an international standard.

       The specification of optimization has been subject to changes through
       early proposals. At one time, -O and -N were Booleans: optimize and do
       not optimize (with an unspecified default). Some historical practice
       led this to be changed to:

       -O 0      No optimization.

       -O 1      Some level of optimization.

       -O _n      Other, unspecified levels of optimization.

       It is not always clear whether ``good code generation'' is the same
       thing as optimization. Simple optimizations of local actions do not
       usually affect the semantics of a program. The -O 0 option has been
       included to accommodate the very particular nature of scientific
       calculations in a highly optimized environment; compilers make errors.
       Some degree of optimization is expected, even if it is not documented
       here, and the ability to shut it off completely could be important when
       porting an application. An implementation may treat -O 0 as ``do less
       than normal'' if it wishes, but this is only meaningful if any of the
       operations it performs can affect the semantics of a program. It is
       highly dependent on the implementation whether doing less than normal
       is logical. It is not the intent of the -O 0 option to ask for
       inefficient code generation, but rather to assure that any semantically
       visible optimization is suppressed.

       The specification of standard library access is consistent with the C
       compiler specification. Implementations are not required to have
       /usr/lib/libf.a, as many historical implementations do, but if not they
       are required to recognize ff as a token.

       External symbol size limits are in normative text; conforming
       applications need to know these limits. However, the minimum maximum
       symbol length should be taken as a constraint on a conforming
       application, not on an implementation, and consequently the action
       taken for a symbol exceeding the limit is unspecified. The minimum size
       for the external symbol table was added for similar reasons.

       The CONSEQUENCES OF ERRORS section clearly specifies the behavior of
       the compiler when compilation or link-edit errors occur. The behavior
       of several historical implementations was examined, and the choice was
       made to be silent on the status of the executable, or a.out, file in
       the face of compiler or linker errors. If a linker writes the
       executable file, then links it on disk with lseek()s and write()s, the
       partially linked executable file can be left on disk and its execute
       bits turned off if the link edit fails. However, if the linker links
       the image in memory before writing the file to disk, it need not touch
       the executable file (if it already exists) because the link edit fails.
       Since both approaches are historical practice, a conforming application
       shall rely on the exit status of fort77, rather than on the existence
       or mode of the executable file.

       The -g and -s options are not specified as mutually-exclusive.
       Historically, these two options have been mutually-exclusive, but
       because both are so loosely specified, it seemed appropriate to leave
       their interaction unspecified.

       The requirement that conforming applications specify compiler options
       separately is to reserve the multi-character option name space for
       vendor-specific compiler options, which are known to exist in many
       historical implementations. Implementations are not required to
       recognize, for example, -gc as if it were -g -c; nor are they forbidden
       from doing so. The SYNOPSIS shows all of the options separately to
       highlight this requirement on applications.

       Echoing filenames to standard error is considered a diagnostic message
       because it would otherwise be difficult to associate an error message
       with the erring file. They are described with ``may'' to allow
       implementations to use other methods of identifying files and to
       parallel the description in c99.

FUTURE DIRECTIONS
       Future versions of this standard may withdraw this utility. There are
       implementations of compilers that conform to much more recent versions
       of the FORTRAN programming language. Since there is no active FORTRAN
       binding to POSIX.1-2008, this standard does not need to specify any
       compiler.

SEE ALSO
       ar, asa, c99, umask

       The Base Definitions volume of POSIX.1-2017, Chapter _8, Environment
       Variables, Section 12.2, Utility Syntax Guidelines

       The System Interfaces volume of POSIX.1-2017, exec

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  In the event of any discrepancy between this version and the
       original IEEE and The Open Group Standard, the original IEEE and The
       Open Group Standard is the referee document. The original Standard can
       be obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .



IEEE/The Open Group                  2017                            FORT77(1)
