32v 1m m4

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M4(1) UNIX Programmer's Manual M4(1)


    m4 - macro processor


    m4 [ files ]


    _M_4 is a macro processor intended as a front end for Ratfor,
    C, and other languages.  Each of the argument files is pro-
    cessed in order; if there are no arguments, or if an argu-
    ment is `-', the standard input is read.  The processed text
    is written on the standard output.
    Macro calls have the form
         name(arg1,arg2, . . . , argn)
    The `(' must immediately follow the name of the macro.  If a
    defined macro name is not followed by a `(', it is deemed to
    have no arguments.  Leading unquoted blanks, tabs, and new-
    lines are ignored while collecting arguments.  Potential
    macro names consist of alphabetic letters, digits, and
    underscore `_', where the first character is not a digit.
    Left and right single quotes (`') are used to quote strings.
    The value of a quoted string is the string stripped of the
    When a macro name is recognized, its arguments are collected
    by searching for a matching right parenthesis.  Macro
    evaluation proceeds normally during the collection of the
    arguments, and any commas or right parentheses which happen
    to turn up within the value of a nested call are as effec-
    tive as those in the original input text.  After argument
    collection, the value of the macro is pushed back onto the
    input stream and rescanned.
    _M_4 makes available the following built-in macros.  They may
    be redefined, but once this is done the original meaning is
    lost.  Their values are null unless otherwise stated.
    define    The second argument is installed as the value of
              the macro whose name is the first argument.  Each
              occurrence of $_n in the replacement text, where _n
              is a digit, is replaced by the _n-th argument.
              Argument 0 is the name of the macro; missing argu-
              ments are replaced by the null string.
    undefine  removes the definition of the macro named in its
    ifdef     If the first argument is defined, the value is the
              second argument, otherwise the third.  If there is
              no third argument, the value is null.  The word
              _u_n_i_x is predefined on UNIX versions of _m_4.
              Change quote characters to the first and second
              arguments.  _C_h_a_n_g_e_q_u_o_t_e without arguments restores
              the original values (i.e., `').
    divert    _M_4 maintains 10 output streams, numbered 0-9.  The
              final output is the concatenation of the streams
              in numerical order; initially stream 0 is the
              current stream.  The _d_i_v_e_r_t macro changes the
              current output stream to its (digit-string) argu-
              ment.  Output diverted to a stream other than 0
              through 9 is discarded.
    undivert  causes immediate output of text from diversions
              named as arguments, or all diversions if no argu-
              ment.  Text may be undiverted into another diver-
              sion.  Undiverting discards the diverted text.
    divnum    returns the value of the current output stream.
    dnl       reads and discards characters up to and including
              the next newline.
    ifelse    has three or more arguments.  If the first argu-
              ment is the same string as the second, then the
              value is the third argument.  If not, and if there
              are more than four arguments, the process is
              repeated with arguments 4, 5, 6 and 7.  Otherwise,
              the value is either the fourth string, or, if it
              is not present, null.
    incr      returns the value of its argument incremented by
              1.  The value of the argument is calculated by
              interpreting an initial digit-string as a decimal
    eval      evaluates its argument as an arithmetic expres-
              sion, using 32-bit arithmetic.  Operators include
              +, -, *, /, %, ^ (exponentiation); relationals;
    len       returns the number of characters in its argument.
    index     returns the position in its first argument where
              the second argument begins (zero origin), or -1 if
              the second argument does not occur.
    substr    returns a substring of its first argument.  The
              second argument is a zero origin number selecting
              the first character; the third argument indicates
              the length of the substring.  A missing third
              argument is taken to be large enough to extend to
              the end of the first string.
    translit  transliterates the characters in its first argu-
              ment from the set given by the second argument to
              the set given by the third.  No abbreviations are
    include   returns the contents of the file named in the
    sinclude  is identical to _i_n_c_l_u_d_e, except that it says noth-
              ing if the file is inaccessible.
    syscmd    executes the UNIX command given in the first argu-
              ment.  No value is returned.
    maketemp  fills in a string of XXXXX in its argument with
              the current process id.
    errprint  prints its argument on the diagnostic output file.
    dumpdef   prints current names and definitions, for the
              named items, or for all if no arguments are given.


    B. W. Kernighan and D. M. Ritchie, _T_h_e _M_4 _M_a_c_r_o _P_r_o_c_e_s_s_o_r