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



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

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 lan-
       guage 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
       IEEE Std 1003.1-2001, 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 IEEE Std 1003.1-2001, 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
              IEEE Std 1003.1-2001  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 unspeci-
              fied. 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.f The pathname of a FORTRAN source file to be compiled and optionally passed to the link editor. The file-
              name 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. Implementa-
              tions 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  recog-
              nize 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:


              liblibrary.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. Implemen-
       tations 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 inter-
       pret 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 IEEE Std 1003.1-2001, Section 8.2, Internationalization Variables for  the  prece-
              dence 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  exam-
              ple, 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 writ-
              ten 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 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 implementa-
       tion-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 implementa-
       tion-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  com-
       pile  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  norma-
       tive  reference because the ISO/IEC version of FORTRAN-77 has been superseded by the ISO/IEC 1539:1990 standard
       (Fortran-90).

       The file inclusion and symbol definition #define mechanisms used by the c99 utility were not included  in  this
       volume of IEEE Std 1003.1-2001-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 IEEE Std 1003.1-2001, even though many  historical  com-
       pilers  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 IEEE Std 1003.1-2001 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.  Conse-
       quently, 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 prepro-
       cessing 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  accom-
       modate  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 logi-
       cal. 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 imple-
       mentation,  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 mutu-
       ally-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-char-
       acter 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
       A  compilation  system based on the ISO/IEC 1539:1990 standard (Fortran-90) may be considered for a future ver-
       sion; it may have a different utility name from fort77.

SEE ALSO
       ar, asa, c99, umask(), the System Interfaces volume of IEEE Std 1003.1-2001, exec

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Stan-
       dard  for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifica-
       tions Issue 6, Copyright (C) 2001-2003 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 Stan-
       dard, 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 .



IEEE/The Open Group                  2003                           FORT77(1P)