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m4(1)									 m4(1)

       m4 - Preprocesses files, expanding macro definitions

       m4 [-Bnumber] [-es] [-Hnumber] [-Snumber] [-Tnumber] [-Dmacro] [=value]
       [-Umacro] file... | -

       [XPG4-UNIX]  The m4 command is a macro processor used as a preprocessor
       for C and other languages.

       Interfaces  documented on this reference page conform to industry stan‐
       dards as follows:

       m4:  XPG4, XPG4-UNIX

       Refer to the standards(5) reference page	 for  more  information	 about
       industry standards and associated tags.

       [Tru64 UNIX]  Makes number the size of the push-back and parameter col‐
       lection buffers (the default is 4096).  [Tru64 UNIX]  Operates interac‐
       tively.	Interrupts are ignored and the output is not buffered.	[Tru64
       UNIX]  Makes number the size  of	 the  symbol  table  hash  array  (the
       default	  is	199).	  The	size   must   be   a   prime   number.
       [XPG4-UNIX]  Enables the	 line  sync  output  for  the  C  preprocessor
       (#line...).  [Tru64 UNIX]  Makes number the size of the call stack (the
       default is 800 slots).  Macros take three slots, and nonmacro arguments
       take one.  [Tru64 UNIX]	Makes number the size of the token buffer (the
       default is 512 bytes).  [XPG4-UNIX]  Defines macro as value.  If	 value
       is  not specified, macro becomes null.  [XPG4-UNIX]  Undefines a built-
       in macro or one previously defined with the -D option.


       [XPG4-UNIX]  The order of options is significant.  If used, the	-D  or
       -U  options must appear after any other options and before any file op‐

       [XPG4-UNIX]  Pathname of a file to be processed.	 If file  is  omitted,
       standard input is used.	[XPG4-UNIX]  Read standard input.

       [XPG4-UNIX]  You	 can use m4 to process built-in macros or user-defined
       macros.	Each file is processed in order.  If you do not specify a file
       or  if you give a dash (-) as a filename, the m4 command reads standard
       input.  It writes the processed macros to standard output.

       [XPG4-UNIX]  Macro calls follow the form: macro(argument...)

       [XPG4-UNIX]  The left parenthesis must immediately  follow  macro.   If
       the  left  parenthesis does not follow the name of a defined macro, the
       m4 command reads it as a macro call with	 no  arguments.	  Macro	 names
       consist	of  ASCII  alphabetic  letters, digits, and the underscore (_)
       character.  Extended characters are not allowed in  macro  names.   The
       first character cannot be a digit.

       [XPG4-UNIX]  While   collecting	 arguments,  the  m4  command  ignores
       unquoted leading spaces, tabs,  and  newline  characters.   Use	single
       quotes  ('')  to	 quote	strings.   The value of a quoted string is the
       string with the quotation marks stripped off.

       [XPG4-UNIX]  When the m4 command recognizes a macro, it collects	 argu‐
       ments  by  searching  for  a matching right parenthesis.	 If you supply
       fewer arguments than appear in the macro definition, m4	considers  the
       trailing arguments in the definition to be null.	 Macro evaluation pro‐
       ceeds normally during the collection of the arguments.  All  commas  or
       right parentheses within the value of a nested call are translated lit‐
       erally; they do not need an escape character or quotation marks.	 After
       collecting arguments, the m4 command pushes the value of the macro back
       onto the input stream and scans again.

   Built-In Macros
       [XPG4-UNIX]  The m4 command contains  the  following  built-in  macros.
       You can redefine them, but they will then lose their original meanings.
       The  values  of	these  macros  are  null  unless   otherwise   stated:
       [XPG4-UNIX]  Replaces  the macro macro with the value of new_name.  The
       new_name string can included tokens of the form $n...  (where  n	 is  a
       digit).	In this case, each occurrence of $n in the replacement text is
       replaced by the n-th argument of macro.	The name of the macro  is  $0.
       The  null  string  replaces missing arguments.  The number of arguments
       replaces $#.  A list of all arguments, separated	 by  commas,  replaces
       $*.   The $@ acts like $*, but each argument is quoted with the current
       quotation character (see the changequote macro).	  [XPG4-UNIX]  Removes
       the  definition	of  macro (including those preserved using the pushdef
       macro).	 [XPG4-UNIX]  Returns  the   quoted   definition   of	macro.
       [XPG4-UNIX]  If	the first argument is defined, the value is the second
       argument.  Otherwise, the value is the third argument.  If there is  no
       third argument, the value is null.

	      [Tru64   UNIX]  Note   that   the	  word	 unix  is  predefined.
	      [XPG4-UNIX]  Redefines macro with new_name  as  in  define,  but
	      saves any previous definition.  [XPG4-UNIX]  Removes the current
	      definition of macro and returns to the previous  definition,  if
	      one  existed.   [XPG4-UNIX]  Returns all but the first argument.
	      The other arguments are quoted and pushed back  with  commas  in
	      between.	 The  quoting  nullifies  the effect of the extra scan
	      that is subsequently  performed.	 [XPG4-UNIX]  The  changequote
	      macro  sets  the	begin  and end symbols. With no arguments, the
	      quote strings are set to the default values (that	 is,  `',  one
	      grave  accent  and one apostrophe). With a single argument, that
	      argument becomes the begin-quote string and the newline  charac‐
	      ter  becomes the end-quote string. With two arguments, the first
	      argument becomes the begin-quote string and the second  argument
	      becomes  the  end-quote  string.	The  symbols can be up to five
	      bytes long.  [XPG4-UNIX]	Changes left and right comment markers
	      from  the	 default  #  and newline character to left_comment and
	      right_comment. With no arguments, the comment mechanism is  dis‐
	      abled.  With one argument, the left marker becomes the parameter
	      and the right marker becomes  a  newline	character.   With  two
	      arguments, both markers are affected.  Comment markers can be up
	      to 5 bytes long.	[XPG4-UNIX]  Changes the current output stream
	      to stream number.	 There are 10 output streams, numbered 0 to 9.
	      The final output is the concatenation of the streams in  numeri‐
	      cal  order.  Initially,  stream  zero (0) is the current stream.
	      The m4 command discards output diverted to a stream other than 0
	      to  9.   [XPG4-UNIX]  Causes  immediate  output of text from the
	      specified diversions (or all diversions if  there	 is  no	 argu‐
	      ment).   Text  can  be undiverted into another diversion.	 Undi‐
	      verting discards the diverted  text.   [XPG4-UNIX]  Returns  the
	      value of the current output stream.  [XPG4-UNIX]	Reads and dis‐
	      cards characters up to and including the next newline character.
	      [XPG4-UNIX]  If string1 and string2 are the same, then the value
	      is true.	If they are not and if there are more than four	 argu‐
	      ments,  m4 repeats the process with the additional arguments (4,
	      5, 6, and so on).	 Otherwise, the value is either false or  null
	      if  you  provide	no  value for false.  [XPG4-UNIX]  Returns the
	      value of its argument incremented	 by  1.	  [XPG4-UNIX]  Returns
	      the value of its argument decreased by 1.


	      [XPG4-UNIX]  Evaluates  its  first  argument  as	an  arithmetic
	      expression, using 32-bit (long) arithmetic.  The	operators  you
	      can use include +, -, *, /, %, ^ (exponentiation), bitwise &, |,
	      ~, and ^ relationals, and parentheses.

	      [XPG4-UNIX]  Octal and hex numbers can be specified as in C. The
	      optional	number1	 specifies  the	 radix	for  the result of the
	      expression.  The default radix  is  10.	The  optional  number2
	      specifies	 the  minimum  number  of  digits  in the result.  The
	      default is 1.   [XPG4-UNIX]  Returns  the	 number	 of  bytes  in
	      string.  [Tru64 UNIX]  Returns the number of displayable charac‐
	      ters in string; that is, 2-byte extended characters are  counted
	      as  one  displayable  character.	[XPG4-UNIX]  Returns the first
	      position in string1, where string2 begins (zero origin),	or  -1
	      if  the  second argument does not occur.	[XPG4-UNIX]  Returns a
	      substring of string.  The beginning of the substring is selected
	      with position, and number indicates the length of the substring.
	      Without number, the substring includes everything to the end  of
	      the first string.	 [XPG4-UNIX]  Transliterates the characters in
	      string from the set given by from to the set given  by  to.   No
	      abbreviations  are  permitted.   2-byte  extended characters are
	      correctly mapped into the corresponding replacement  characters.
	      [XPG4-UNIX]  Returns  the	 contents of file or displays an error
	      message if it cannot access the file.  [XPG4-UNIX]  Returns  the
	      contents of file, but it gives no error message if file is inac‐
	      cessible.	 [XPG4-UNIX]  Runs the specified operating system com‐
	      mand.   No value is returned, but sysval can be used to retrieve
	      the exit value.  [XPG4-UNIX]  Returns the return code  from  the
	      last  call  to syscmd.  [XPG4-UNIX]  Replaces xxxxx in its argu‐
	      ment with the current process ID number where  xxxxx  represents
	      any    number    of    numeric   or   alphanumeric   characters.
	      [XPG4-UNIX]  Exits from m4 immediately, returning the  specified
	      exit  value  (the	 default  is  zero (0)).  [XPG4-UNIX]  Sets or
	      resets last_macro, which is run after  reading  the  End-of-File
	      character.   For	example:  m4wrap(`cleanup()') sets the cleanup
	      macro at the end of m4.  [XPG4-UNIX]  Includes  message  on  the
	      diagnostic output file (standard error).	[XPG4-UNIX]  Writes to
	      standard output the current names and definitions for the	 named
	      items   or   for	 all  items  if	 no  arguments	are  provided.
	      [XPG4-UNIX]  Turns on tracing for	 macro.	  If  none  is	named,
	      tracing	 is    turned	 on    for   all   macro   expansions.
	      [XPG4-UNIX]  Turns off trace globally and for any	 macro	speci‐
	      fied.   Macros  specifically  traced  by traceon can be untraced
	      only by specific calls to traceoff.

       [XPG4-UNIX]  Successful completion.  [XPG4-UNIX]	 An error occurred.

       [XPG4-UNIX]  If you use the m4exit macro, the input  file  can  specify
       the exit value.

       To  preprocess  a  C language program with m4 and compile it, enter: m4
       prog.m4 >prog.c cc prog.c

       The  following  environment  variables  affect  the  execution  of  m4:
       [XPG4-UNIX]  Provides  a	 default  value	 for  the internationalization
       variables that are unset or null. If LANG is unset or null, the	corre‐
       sponding	 value from the default locale is used. If any of the interna‐
       tionalization variables contain an invalid setting, the utility behaves
       as if none of the variables had been defined.  [XPG4-UNIX]  If set to a
       non-empty string value, overrides the values of all the other  interna‐
       tionalization  variables.   [XPG4-UNIX]	Determines  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).
       [XPG4-UNIX]  Determines the locale for the format and contents of diag‐
       nostic messages written to standard error.  [XPG4-UNIX]	Determines the
       location of message catalogues for the processing of LC_MESSAGES.

       Commands:  c89(1), cc(1), cpp(1)

       Standards:  standards(5)


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