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PROLOG | NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | STDIN | INPUT FILES | ENVIRONMENT VARIABLES | ASYNCHRONOUS EVENTS | STDOUT | STDERR | OUTPUT FILES | EXTENDED DESCRIPTION | EXIT STATUS | CONSEQUENCES OF ERRORS | APPLICATION USAGE | EXAMPLES | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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FORT77(1P) POSIX Programmer's Manual FORT77(1P)
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.
fort77 — FORTRAN compiler (FORTRAN)
fort77 [-c] [-g] [-L directory]... [-O optlevel] [-o outfile] [-s]
[-w] operand...
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.1‐2017, 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.
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 '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.
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:
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.
Not used.
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
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.
Default.
Not used.
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.
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 unspecified.
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.
None.
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
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 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.
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.
ar(1p), asa(1p), c99(1p), umask(1p)
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(1p)
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(1P)
Pages that refer to this page: ar(1p), asa(1p), ctags(1p), strip(1p)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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