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C99(P) C99(P)
NAME
c99 - compile standard C programs
SYNOPSIS
c99 [-c][-D name[=value]]...[-E][-g][-I directory] ... [-L directory]
... [-o outfile][-Ooptlevel][-s][-U name]... operand ...
DESCRIPTION
The c99 utility is an interface to the standard C compilation system; it shall
accept source code conforming to the ISO C standard. The system conceptually con-
sists of a compiler and link editor. The files referenced by operands shall be com-
piled and linked to produce an executable file. (It is unspecified whether the
linking occurs entirely within the operation of c99; some implementations may pro-
duce objects that are not fully resolved until the file is executed.)
If the -c option is specified, for all pathname operands of the form file .c, the
files:
$(basename pathname .c).o
shall be created 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 .c operands.
If there are no options that prevent link editing (such as -c or -E), and all
operands compile and link without error, the resulting executable file shall be
written according to the -o outfile option (if present) or to the file a.out.
The executable file shall be created as specified in File Read, Write, and Creation
, except that the file permission bits shall be set to:
S_IRWXO | S_IRWXG | S_IRWXU
and the bits specified by the umask of the process shall be cleared.
OPTIONS
The c99 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 -I and -L options is significant.
* Conforming applications shall specify each option separately; that is, grouping
option letters (for example, -cO) 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 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 or -E, the result is
unspecified.
-D name[=value]
Define name as if by a C-language #define directive. If no = value is given,
a value of 1 shall be used. The -D option has lower precedence than the -U
option. That is, if name is used in both a -U and a -D option, name shall be
undefined regardless of the order of the options. Additional implementation-
defined names may be provided by the compiler. Implementations shall support
at least 2048 bytes of -D definitions and 256 names.
-E Copy C-language source files to standard output, expanding all preprocessor
directives; no compilation shall be performed. If any operand is not a text
file, the effects are unspecified.
-I directory
Change the algorithm for searching for headers whose names are not absolute
pathnames to look in the directory named by the directory pathname before
looking in the usual places. Thus, headers whose names are enclosed in dou-
ble-quotes ( "" ) shall be searched for first in the directory of the file
with the #include line, then in directories named in -I options, and last in
the usual places. For headers whose names are enclosed in angle brackets (
"<>" ), the header shall be searched for only in directories named in -I
options and then in the usual places. Directories named in -I options shall
be searched in the order specified. Implementations shall support at least
ten instances of this option in a single c99 command invocation.
-L directory
Change the algorithm of searching for the libraries named in the -l objects
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
order specified. Implementations shall support at least ten instances of
this option in a single c99 command invocation. If a directory specified by
a -L option contains files named libc.a, libm.a, libl.a, or liby.a, the
results are unspecified.
-O optlevel
Specify the level of code optimization. If the optlevel option-argument is
the digit â€â€™0â€â€™ , all special code optimizations shall be disabled. If it is
the digit â€â€™1â€â€™ , 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.
-U name
Remove any initial definition of name.
Multiple instances of the -D, -I, -U, and -L options can be specified.
OPERANDS
An operand is either in the form of a pathname or the form -l library. The applica-
tion shall ensure that at least one operand of the pathname form is specified. The
following operands shall be supported:
file.c A C-language source file to be compiled and optionally linked. The applica-
tion shall ensure that the operand is of this form if the -c option is used.
file.a A library of object files typically produced by the ar utility, 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 c99 -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 shall be 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 a C-language
source program, an object file in the format produced by c99 -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 file formats are implementation-defined.
ENVIRONMENT VARIABLES
The following environment variables shall affect the execution of c99:
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 interna-
tionalization 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 char-
acters 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 Provide a pathname that should override the default directory for temporary
files, if any. On XSI-conforming systems, provide a pathname that shall
override the default directory for temporary files, if any.
ASYNCHRONOUS EVENTS
Default.
STDOUT
If more than one file operand ending in .c (or possibly other unspecified suffixes)
is given, for each such file:
"%s:\n", <file>
may be written. These messages, if written, shall precede the processing of each
input file; they shall not be written to the standard output if they are written to
the standard error, as described in the STDERR section.
If the -E option is specified, the standard output shall be a text file that repre-
sents the results of the preprocessing stage of the language; it may contain extra
information appropriate for subsequent compilation passes.
STDERR
The standard error shall be used only for diagnostic messages. If more than one
file operand ending in .c (or possibly other unspecified suffixes) is given, for
each such file:
"%s:\n", <file>
may be written to allow identification of the diagnostic and warning messages with
the appropriate input file. These messages, if written, shall precede the process-
ing of each input file; they shall not be written to the standard error if they are
written to the standard output, as described in the STDOUT section.
This utility may produce warning messages about certain conditions that do not war-
rant returning an error (non-zero) exit value.
OUTPUT FILES
Object files or executable files or both are produced in unspecified formats.
EXTENDED DESCRIPTION
Standard Libraries
The c99 utility shall recognize the following -l operands for standard libraries:
-l c This operand shall make visible all functions referenced in the System
Interfaces volume of IEEE Std 1003.1-2001, with the possible exception of
those functions listed as residing in <aio.h>, <arpa/inet.h>, <complex.h>,
<fenv.h>, <math.h>, <mqueue.h>, <netdb.h>, <netinet/in.h>, <pthread.h>,
<sched.h>, <semaphore.h>, <spawn.h>, <sys/socket.h>, pthread_kill(), and
pthread_sigmask() in <signal.h>, <trace.h>, functions marked as extensions
other than as part of the MF or MPR extensions in <sys/mman.h>, functions
marked as ADV in <fcntl.h>, and functions marked as CS, CPT, and TMR in
<time.h>. This operand shall not be required to be present to cause a search
of this library.
-l l This operand shall make visible all functions required by the C-language
output of lex that are not made available through the -l c operand.
-l pthread
This operand shall make visible all functions referenced in <pthread.h> and
pthread_kill() and pthread_sigmask() referenced in <signal.h>. An implemen-
tation may search this library in the absence of this operand.
-l m This operand shall make visible all functions referenced in <math.h>, <com-
plex.h>, and <fenv.h>. An implementation may search this library in the
absence of this operand.
-l rt This operand shall make visible all functions referenced in <aio.h>,
<mqueue.h>, <sched.h>, <semaphore.h>, and <spawn.h>, functions marked as
extensions other than as part of the MF or MPR extensions in <sys/mman.h>,
functions marked as ADV in <fcntl.h>, and functions marked as CS, CPT, and
TMR in <time.h>. An implementation may search this library in the absence of
this operand.
-l trace
This operand shall make visible all functions referenced in <trace.h>. An
implementation may search this library in the absence of this operand.
-l xnet
This operand makes visible all functions referenced in <arpa/inet.h>,
<netdb.h>, <netinet/in.h>, and <sys/socket.h>. An implementation may search
this library in the absence of this operand.
-l y This operand shall make visible all functions required by the C-language
output of yacc that are not made available through the -l c operand.
In the absence of options that inhibit invocation of the link editor, such as -c or
-E, the c99 utility shall cause the equivalent of a -l c 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 libraries libc.a, libm.a, librt.a, libpthread.a,
libl.a, liby.a, or libxnet.a exist as regular files. The implementation may accept
as -l operands names of objects that do not exist as regular files.
External Symbols
The C compiler and link editor shall support the significance of external symbols
up to a length of at least 31 bytes; 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 in total. A diagnos-
tic message shall be written to the standard output if the implementation-defined
limit is exceeded; other actions are unspecified.
Programming Environments
All implementations shall support one of the following programming environments as
a default. Implementations may support more than one of the following programming
environments. Applications can use sysconf() or getconf to determine which program-
ming environments are supported.
Table: Programming Environments: Type Sizes
Programming Environment Bits in Bits in Bits in Bits in
getconf Name int long pointer off_t
_POSIX_V6_ILP32_OFF32 32 32 32 32
_POSIX_V6_ILP32_OFFBIG 32 32 32 >=64
_POSIX_V6_LP64_OFF64 32 64 64 64
_POSIX_V6_LPBIG_OFFBIG >=32 >=64 >=64 >=64
All implementations shall support one or more environments where the widths of the
following types are no greater than the width of type long: blksize_t, cc_t,
mode_t, nfds_t, pid_t, ptrdiff_t, size_t, speed_t, ssize_t, suseconds_t, tcflag_t,
useconds_t, wchar_t, wint_t
The executable files created when these environments are selected shall be in a
proper format for execution by the exec family of functions. Each environment may
be one of the ones in Programming Environments: Type Sizes , or it may be another
environment. The names for the environments that meet this requirement shall be
output by a getconf command using the _POSIX_V6_WIDTH_RESTRICTED_ENVS argument. If
more than one environment meets the requirement, the names of all such environments
shall be output on separate lines. Any of these names can then be used in a subse-
quent getconf command to obtain the flags specific to that environment with the
following suffixes added as appropriate:
_CFLAGS
To get the C compiler flags.
_LDFLAGS
To get the linker/loader flags.
_LIBS To get the libraries.
This requirement may be removed in a future version of IEEE Std 1003.1.
When this utility processes a file containing a function called main(), it shall be
defined with a return type equivalent to int. Using return from the initial call to
main() shall be equivalent (other than with respect to language scope issues) to
calling exit() with the returned value. Reaching the end of the initial call to
main() shall be equivalent to calling exit(0). The implementation shall not declare
a prototype for this function.
Implementations provide configuration strings for C compiler flags, linker/loader
flags, and libraries for each supported environment. When an application needs to
use a specific programming environment rather than the implementation default pro-
gramming environment while compiling, the application shall first verify that the
implementation supports the desired environment. If the desired programming envi-
ronment is supported, the application shall then invoke c99 with the appropriate C
compiler flags as the first options for the compile, the appropriate linker/loader
flags after any other options but before any operands, and the appropriate
libraries at the end of the operands.
Conforming applications shall not attempt to link together object files compiled
for different programming models. Applications shall also be aware that binary data
placed in shared memory or in files might not be recognized by applications built
for other programming models.
Table: Programming Environments: c99 and cc Arguments
Programming Environment c99 and cc Arguments
getconf Name Use getconf Name
_POSIX_V6_ILP32_OFF32 C Compiler Flags POSIX_V6_ILP32_OFF32_CFLAGS
Linker/Loader Flags POSIX_V6_ILP32_OFF32_LDFLAGS
Libraries POSIX_V6_ILP32_OFF32_LIBS
_POSIX_V6_ILP32_OFFBIG C Compiler Flags POSIX_V6_ILP32_OFFBIG_CFLAGS
Linker/Loader Flags POSIX_V6_ILP32_OFFBIG_LDFLAGS
Libraries POSIX_V6_ILP32_OFFBIG_LIBS
_POSIX_V6_LP64_OFF64 C Compiler Flags POSIX_V6_LP64_OFF64_CFLAGS
Linker/Loader Flags POSIX_V6_LP64_OFF64_LDFLAGS
Libraries POSIX_V6_LP64_OFF64_LIBS
_POSIX_V6_LPBIG_OFFBIG C Compiler Flags POSIX_V6_LPBIG_OFFBIG_CFLAGS
Linker/Loader Flags POSIX_V6_LPBIG_OFFBIG_LDFLAGS
Libraries POSIX_V6_LPBIG_OFFBIG_LIBS
EXIT STATUS
The following exit values shall be returned:
0 Successful compilation or link edit.
>0 An error occurred.
CONSEQUENCES OF ERRORS
When c99 encounters a compilation error that causes an object file not to be cre-
ated, it shall write a diagnostic to standard error and continue to compile other
source code operands, but it shall not perform the link phase and return a non-zero
exit status. If the link edit is unsuccessful, a diagnostic message shall be writ-
ten to standard error and c99 exits with a non-zero status. A conforming applica-
tion shall rely on the exit status of c99, rather than on the existence or mode of
the executable file.
The following sections are informative.
APPLICATION USAGE
Since the c99 utility usually creates files in the current directory during the
compilation process, it is typically necessary to run the c99 utility in a direc-
tory in which a file can be created.
On systems providing POSIX Conformance (see the Base Definitions volume of
IEEE Std 1003.1-2001, Chapter 2, Conformance), c99 is required only with the C-Lan-
guage Development option; XSI-conformant systems always provide c99.
Some historical implementations have created .o files when -c is not specified and
more than one source file is given. Since this area is left unspecified, the appli-
cation cannot rely on .o files being created, but it also must be prepared for any
related .o files that already exist being deleted at the completion of the link
edit.
Some historical implementations have permitted -L options to be interspersed with
-l operands on the command line. For an application to compile consistently on
systems that do not behave like this, it is necessary for a conforming application
to supply all -L options before any of the -l options.
There is the possible implication that if a user supplies versions of the standard
functions (before they would be encountered by an implicit -l c or explicit -l m),
that those versions would be used in place of the standard versions. There are
various reasons this might not be true (functions defined as macros, manipulations
for clean name space, and so on), so the existence of files named in the same man-
ner as the standard libraries within the -L directories is explicitly stated to
produce unspecified behavior.
All of the functions specified in the System Interfaces volume of
IEEE Std 1003.1-2001 may be made visible by implementations when the Standard C
Library is searched. Conforming applications must explicitly request searching the
other standard libraries when functions made visible by those libraries are used.
EXAMPLES
1. The following usage example compiles foo.c and creates the executable file foo:
c99 -o foo foo.c
The following usage example compiles foo.c and creates the object file foo.o:
c99 -c foo.c
The following usage example compiles foo.c and creates the executable file a.out:
c99 foo.c
The following usage example compiles foo.c, links it with bar.o, and creates the
executable file a.out. It may also create and leave foo.o:
c99 foo.c bar.o
2. The following example shows how an application using threads interfaces can
test for support of and use a programming environment supporting 32-bit int,
long, and pointer types and an off_t type using at least 64 bits:
if [ $(getconf _POSIX_V6_ILP32_OFFBIG) != "-1" ]
then
c99 $(getconf POSIX_V6_ILP32_OFFBIG_CFLAGS) -D_XOPEN_SOURCE=600 \
$(getconf POSIX_V6_ILP32_OFFBIG_LDFLAGS) foo.c -o foo \
$(getconf POSIX_V6_ILP32_OFFBIG_LIBS) -l pthread
else
echo ILP32_OFFBIG programming environment not supported
exit 1
fi
3. The following examples clarify the use and interactions of -L options and -l
operands.
Consider the case in which module a.c calls function f() in library libQ.a, and
module b.c calls function g() in library libp.a. Assume that both libraries reside
in /a/b/c. The command line to compile and link in the desired way is:
c99 -L /a/b/c main.o a.c -l Q b.c -l p
In this case the -l Q operand need only precede the first -l p operand, since both
libQ.a and libp.a reside in the same directory.
Multiple -L operands can be used when library name collisions occur. Building on
the previous example, suppose that the user wants to use a new libp.a, in /a/a/a,
but still wants f() from /a/b/c/libQ.a:
c99 -L /a/a/a -L /a/b/c main.o a.c -l Q b.c -l p
In this example, the linker searches the -L options in the order specified, and
finds /a/a/a/libp.a before /a/b/c/libp.a when resolving references for b.c. The
order of the -l operands is still important, however.
4. The following example shows how an application can use a programming environ-
ment where the widths of the following types: blksize_t, cc_t, mode_t, nfds_t,
pid_t, ptrdiff_t, size_t, speed_t, ssize_t, suseconds_t, tcflag_t, useconds_t,
wchar_t, wint_t
are no greater than the width of type long:
# First choose one of the listed environments ...
# ... if there are no additional constraints, the first one will do:
CENV=$(getconf _POSIX_V6_WIDTH_RESTRICTED_ENVS | head -n l)
# ... or, if an environment that supports large files is preferred,
# look for names that contain "OFF64" or "OFFBIG". (This chooses
# the last one in the list if none match.)
for CENV in $(getconf _POSIX_V6_WIDTH_RESTRICTED_ENVS)
do
case $CENV in
*OFF64*|*OFFBIG*) break ;;
esac
done
# The chosen environment name can now be used like this:
c99 $(getconf ${CENV}_CFLAGS) -D _POSIX_C_SOURCE=200112L \
$(getconf ${CENV}_LDFLAGS) foo.c -o foo \
$(getconf ${CENV}_LIBS)
RATIONALE
The c99 utility is based on the c89 utility originally introduced in the
ISO POSIX-2:1993 standard.
Some of the changes from c89 include the modification to the contents of the Stan-
dard Libraries section to account for new headers and options; for example,
<spawn.h> added to the -l rt operand, and the -l trace operand added for the Trac-
ing functions.
FUTURE DIRECTIONS
None.
SEE ALSO
File Read, Write, and Creation , ar , getconf , make , nm , strip , umask() , the
System Interfaces volume of IEEE Std 1003.1-2001, exec, sysconf(), the Base Defini-
tions volume of IEEE Std 1003.1-2001, Chapter 13, Headers
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 original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
POSIX 2003 C99(P)
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