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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 differ (con-
sult 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 language
defined by the ANSI X3.9-1978 standard. The system conceptually consists of a compiler and link editor. The files refer-
enced 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 opti-
mizations 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 val-
ues 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 filename oper-
and 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 imple-
mentation-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 recog-
nize 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 IEEE Std 1003.1-2001, Section 8.2, Internationalization Variables for the precedence of international-
ization 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 stan-
dard 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 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 1539:1990 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 compilers sup-
port 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. 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 com-
piler, and IEEE Std 1003.9-1992 does not specify the military standard or any special preprocessing requirements. Fur-
thermore, 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 Bool-
eans: 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 par-
ticular nature of scientific calculations in a highly optimized environment; compilers make errors. Some degree of opti-
mization 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 mini-
mum maximum symbol length should be taken as a constraint on a conforming application, not on an implementation, and con-
sequently the action taken for a symbol exceeding the limit is unspecified. The minimum size for the external symbol ta-
ble 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 sta-
tus 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 exe-
cute 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-exclu-
sive, 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. Implementa-
tions are not required to recognize, for example, -gc as if it were -g -c; nor are they forbidden from doing so. The SYN-
OPSIS 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 asso-
ciate 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 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, Copy-
right (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 original Standard can be obtained online at http://www.open-
group.org/unix/online.html .
IEEE/The Open Group 2003 FORT77(1P)
