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M4(1)                   FreeBSD General Commands Manual                  M4(1)

     m4 - macro language processor

     m4 [-Dname[=value]] [-Uname] [filename] ...

     The m4 utility is a macro processor that can be used as a front end to
     any language (e.g., C, ratfor, fortran, lex, and yacc).  Each of the
     argument files is processed in order.  If there are no files, or if a
     filename is `-', the standard input is read.  The processed text is sent
     to the standard output.

     Macro calls have the form name(argument1[, argument2, ...,] argumentN).

     There cannot be any space following the macro name and the open
     parentheses '('.  If the macro name is not followed by an open
     parentheses it is processed with no arguments.

     Macro names consist of a leading alphabetic or underscore possibly
     followed by alphanumeric or underscore characters, therefore valid macro
     names match this pattern [a-zA-Z_][a-zA-Z0-9_]*.

     In arguments to macros, leading unquoted space, tab and newline
     characters are ignored.  To quote strings use left and right single
     quotes (e.g., ` this is a string with a leading space').  You can change
     the quote characters with the changequote built-in macro.

     The options are as follows:

     -Dname[=value]     Define the symbol name to have some value (or NULL).

     -Uname             Undefine the symbol name.

     m4 provides the following built-in macros.  They may be redefined, losing
     their original meaning.  Return values are NULL unless otherwise stated.

     changecom       Change the start and end comment sequences.  The default
                     is the pound sign `#' and the newline character.  With no
                     arguments comments are turned off.  The maximum length
                     for a comment marker is five characters.

     changequote     Defines the quote symbols to be the first and second
                     arguments.  Note, only the first character of each
                     argument is used.  If no arguments are given it restores
                     the default open and close single quotes.

     decr            Decrements the argument by 1.  The argument must be a
                     valid numeric string.

     define          Define a new macro named by the first argument to have
                     the value of the second argument.  Each occurrence of $n
                     (where n is 0 through 9) is replaced by the n'th
                     argument.  $0 is the name of the calling macro.
                     Undefined arguments are replaced by a NULL string.  $# is
                     replaced by the number of arguments; $* is replaced by
                     all arguments comma separated; $@ is the same as $* but
                     all arguments are quoted against further expansion.

     defn            Returns the quoted definition for each argument.  This
                     can be used to rename macro definitions (even for built-
                     in macros).

     divert          There are 10 output queues (numbered 0-9).  At the end of
                     processing m4 concatenates all the queues in numerical
                     order to produce the final output.  Initially the output
                     queue is 0.  The divert macro allows you to select a new
                     output queue (an invalid argument passed to divert causes
                     output to be discarded).

     divnum          Returns the current output queue number.

     dnl             Discard input characters up to and including the next

     dumpdef         Prints the names and definitions for the named items, or
                     for everything if no arguments are passed.

     errprint        Prints the first argument on the standard error output

     eval            Computes the first argument as an arithmetic expression
                     using 32-bit arithmetic.  Operators are the standard C
                     ternary, arithmetic, logical, shift, relational, bitwise,
                     and parentheses operators.  You can specify octal,
                     decimal, and hexadecimal numbers as in C.  The second
                     argument (if any) specifies the radix for the result and
                     the third argument (if any) specifies the minimum number
                     of digits in the result.

     expr            This is an alias for eval.

     ifdef           If the macro named by the first argument is defined then
                     return the second argument, otherwise the third.  If
                     there is no third argument, the value is NULL.  The word
                     `unix' is predefined.

     ifelse          If the first argument matches the second argument then
                     ifelse returns the third argument.  If the match fails
                     the three arguments are discarded and the next three
                     arguments are used until there is zero or one arguments
                     left, either this last argument or NULL is returned if no
                     other matches were found.

     include         Returns the contents of the file specified in the first
                     argument.  Include aborts with an error message if the
                     file cannot be included.

     incr            Increments the argument by 1.  The argument must be a
                     valid numeric string.

     index           Returns the index of the second argument in the first
                     argument (e.g., index(the quick brown fox jumped, fox)
                     returns 16).  If the second argument is not found index
                     returns -1.

     len             Returns the number of characters in the first argument.
                     Extra arguments are ignored.

     m4exit          Immediately exits with the return value specified by the
                     first argument, 0 if none.

     m4wrap          Allows you to define what happens at the final EOF,
                     usually for cleanup purposes (e.g.,
                     m4wrap("cleanup(tempfile)") causes the macro cleanup to
                     be invoked after all other processing is done.)

     maketemp        Translates the string XXXXX in the first argument with
                     the current process ID leaving other characters alone.
                     This can be used to create unique temporary file names.

     paste           Includes the contents of the file specified by the first
                     argument without any macro processing.  Aborts with an
                     error message if the file cannot be included.

     popdef          Restores the pushdef'ed definition for each argument.

     pushdef         Takes the same arguments as define, but it saves the
                     definition on a stack for later retrieval by popdef.

     shift           Returns all but the first argument, the remaining
                     arguments are quoted and pushed back with commas in
                     between.  The quoting nullifies the effect of the extra
                     scan that will subsequently be performed.

     sinclude        Similar to include, except it ignores any errors.

     spaste          Similar to paste, except it ignores any errors.

     substr          Returns a substring of the first argument starting at the
                     offset specified by the second argument and the length
                     specified by the third argument.  If no third argument is
                     present it returns the rest of the string.

     syscmd          Passes the first argument to the shell.  Nothing is

     sysval          Returns the return value from the last syscmd.

     translit        Transliterate the characters in the first argument from
                     the set given by the second argument to the set given by
                     the third.  You cannot use tr(1) style abbreviations.

     undefine        Removes the definition for the macro specified by the
                     first argument.

     undivert        Flushes the named output queues (or all queues if no

     unix            A pre-defined macro for testing the OS platform.

     Ozan Yigit <> and
     Richard A. O'Keefe <>

FreeBSD 11.0-PRERELEASE        January 26, 1993        FreeBSD 11.0-PRERELEASE


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