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

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 .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 interac-
	      tions with other options.

       -s     Produce object or executable files, or both, from which symbolic and other informa-
	      tion  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 invoca-
	      tion. 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 gen-
	      erated 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  oper-
       and 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. Imple-
	      mentations  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:

	      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.  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 sup-
       ply 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 IEEE Std 1003.1-2001, Section 8.2, Inter-
	      nationalization 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  interna-
	      tionalization 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  argu-
	      ments and input files).

       LC_MESSAGES
	      Determine the locale that should be used to affect the format and contents of diag-
	      nostic 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 oper-
       and 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  for-
       mats.

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 edi-
       tor 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 encoun-
       tering 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  sta-
       tus,  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 1539:1990 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 imple-
       mented-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  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  con-
       vention	of creating files with .l suffixes collided with historical lex file naming prac-
       tice.

       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 dis-
       cussions, 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  stan-
       dard 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. Further-
       more, 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 semanti-
       cally visible optimization is suppressed.

       The  specification of standard library access is consistent with the C compiler specifica-
       tion. Implementations are not required to have /usr/lib/libf.a, as many historical  imple-
       mentations 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  applica-
       tions.

       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  consid-
       ered for a future version; 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, Standard for Information Technology  --  Portable	Operating  System
       Interface  (POSIX), The Open Group Base Specifications 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
       Standard, the original IEEE and The Open Group Standard is the referee document. The orig-
       inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group			       2003					FORT77(P)
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