fort77(1p) — Linux manual page


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

PROLOG         top

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

NAME         top

       fort77 — FORTRAN compiler (FORTRAN)

SYNOPSIS         top

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

DESCRIPTION         top

       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.f, 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.f 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.1‐2008, except
       that the file permissions shall be set to: S_IRWXO | S_IRWXG |

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

OPTIONS         top

       The fort77 utility shall conform to the Base Definitions volume of
       POSIX.1‐2008, 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.1‐2008 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 '0', all special code
                 optimizations shall be disabled. If it is the digit '1',
                 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         top

       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.f    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.a    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.o    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:


                 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         top

       Not used.

INPUT FILES         top

       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).


       The following environment variables shall affect the execution of

       LANG      Provide a default value for the internationalization
                 variables that are unset or null. (See the Base Definitions
                 volume of POSIX.1‐2008, Section 8.2, Internationalization
                 Variables for the precedence of internationalization
                 variables used to determine the values of locale

       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

                 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.



STDOUT         top

       Not used.

STDERR         top

       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         top

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


   Standard Libraries
       The fort77 utility shall recognize the following −l operand for the
       standard library:

       −l f      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 f
       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

EXIT STATUS         top

       The following exit values shall be returned:

        0    Successful compilation or link edit.

       >0    An error occurred.


       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.



EXAMPLES         top

       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

           fort77 −c xyz.f

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

           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         top

       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.1‐2008—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.1‐2008,
       even though many historical compilers support it, because it is
       derived from FORTRAN-66; it is an anachronism that should not be

       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.1‐2008
       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 f 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.


       A compilation system based on the ISO/IEC 1539:1991 standard may be
       considered for a future version; it may have a different utility name
       from fort77.

SEE ALSO         top

       ar(1p), asa(1p), c99(1p), umask(1p)

       The Base Definitions volume of POSIX.1‐2008, Chapter 8, Environment
       Variables, Section 12.2, Utility Syntax Guidelines

       The System Interfaces volume of POSIX.1‐2008, exec(1p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The Open
       Group Base Specifications Issue 7, Copyright (C) 2013 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
       applied.) 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 .

       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 .

IEEE/The Open Group                 2013                          FORT77(1P)

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