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C99(1P)                    POSIX Programmer's Manual                   C99(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
       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 consists of a compiler and link editor.  The  files  referenced  by
       operands  shall  be  compiled  and linked to produce an executable file. (It is unspecified whether the linking
       occurs entirely within the operation of c99; some implementations  may  produce  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  per-
       mission 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 double-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  '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.

       -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 application  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 application 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. Sev-
       eral 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 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 Provide  a pathname that should override the default directory for temporary files, if any.  On XSI-con-
              forming 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 represents the results of the pre-
       processing 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 processing 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 warrant 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  <sig-
              nal.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 implementation may search this library in the absence of
              this operand.

       -l m   This operand shall make visible all functions referenced in  <math.h>,  <complex.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  exten-
              sions 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 reg-
       ular 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 diagnostic 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 programming 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 subsequent 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  func-
       tion.

       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  programming  environment  while compiling, the application shall first verify that the
       implementation supports the desired environment. If the  desired  programming  environment  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 mod-
       els. Applications shall also be aware that binary data placed in shared memory or in files might not be  recog-
       nized 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 created, it shall write a diagnos-
       tic 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 application 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 typ-
       ically necessary to run the c99 utility in a directory 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-Language Development option; XSI-conformant systems always pro-
       vide 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 application 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  stan-
       dard  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 manner 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 environment 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 Standard 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 Tracing 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 Definitions 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, 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                              C99(1P)