m4(1)m4(1)NAMEm4 - macro processor
SYNOPSIS
[options] [file ...]
DESCRIPTION
is a macro processor intended as a front end for Ratfor, C, and other
languages. Each of the argument files is processed in order; if there
are no files, or if a file name is standard input is read. The pro‐
cessed text is written to standard output.
Options
recognizes the following options:
Operate interactively.
Interrupts are ignored and the output is unbuffered.
Using this mode may be very difficult.
Enable line sync output for the C preprocessor
Change the size of the push-back and argument collection
buffers from the default of 4,096.
Change the size of the symbol table hash array from the
default of 199. The size should be prime.
Change the size of the call stack from the default of 100 slots.
Macros take three slots, and nonmacro arguments take
one.
Change the size of the token buffer from the default of 512
bytes.
To be effective, the options listed above must appear before any
file names and before any or options.
Define name as val or as null if val is omitted.
Undefine name.
Macro Calls
Macro calls have the form:
The left parenthesis must immediately follow the name of the macro. If
the name of a defined macro is not followed by a it is deemed to be a
call of that macro with no arguments. Potential macro names consist of
alphabetic letters, digits, and underscore the first character cannot
be a digit.
Leading unquoted blanks, tabs, and newlines are ignored while collect‐
ing arguments. Left and right single quotes and are used to quote
strings. The value of a quoted string is the string stripped of the
quotes.
When a macro name is recognized, its arguments are collected by search‐
ing for a matching right parenthesis. If fewer arguments are supplied
than are in the macro definition, the trailing arguments are taken to
be null. 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 effective as those in the
original input text. After argument collection, the value of the macro
is pushed back onto the input stream and rescanned.
Built-In Macro Names
makes available the following built-in macros. They can be redefined,
but, once this is done, the original meaning is lost. Their values are
null unless otherwise stated.
Change left and right comment markers from the default
and newline. With no arguments, the comment mecha‐
nism is effectively disabled. With one argument, the
left marker becomes the argument and the right marker
becomes newline. With two arguments, both markers
are affected. Comment markers may be up to five
characters long.
Change quote symbols to the first and second arguments.
The symbols may be up to five characters long. with‐
out arguments restores the original values (i.e., and
Returns the value of its argument decremented by 1.
The second argument is installed as the value of the macro
whose name is the first argument. Each occurrence of
in the replacement text, where n is a digit, is
replaced by the nth argument. Argument 0 is the name
of the macro; missing arguments are replaced by the
null string; is replaced by the number of arguments;
is replaced by a list of all the arguments separated
by commas; is equivalent to but each argument is
quoted (with the current quotes).
Returns the quoted definition of its arguments.
It is useful for renaming macros, especially built-
ins.
maintains 10 output streams, numbered 0 to 9.
The final output is the concatenation of the streams
in numerical order; initially, stream 0 is the cur‐
rent stream. The macro changes the current output
stream to its (digit-string) argument. Output
diverted to a stream other than 0 through 9 is dis‐
carded.
Returns the value of the current output stream.
Reads and discards characters up to and including the next newline.
Prints current names and definitions,
for the named items, or for all if no arguments are
given.
Prints its argument on the diagnostic output file.
Evaluates its argument as an arithmetic expression,
using 32-bit arithmetic. Operators include and rela‐
tionals, and parentheses. Octal and hexadecimal num‐
bers may be specified as in C. The second argument
specifies the radix for the result; the default is
10. The third argument may be used to specify the
minimum number of digits in the result.
Is a predefined object with a null value.
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 is predefined on HP-UX system ver‐
sions of
Has three or more arguments.
If the first argument is the same string as the sec‐
ond, 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.
Returns the contents of the file named in the argument.
Returns the value of its argument incremented by 1.
The value of the argument is calculated by interpret‐
ing an initial digit-string as a decimal number.
Returns the position in its first argument
where the second argument begins (zero origin), or −1
if the second argument does not occur.
Returns the number of characters in its argument.
Causes immediate exit from
Argument 1, if given, is the exit code; the default
is 0.
Argument 1 is pushed back at final EOF;
for example:
Fills in a string of
in its argument with the current process ID.
Removes current definition of its arguments,
exposing the previous one, if any.
Similar to but saves any previous definition.
Returns all but its first argument.
The other arguments are quoted and pushed back with
commas in between. The quoting nullifies the effect
of the extra scan that will subsequently be per‐
formed.
Identical to except that it says nothing if the file is inaccessi‐
ble.
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.
Executes the HP-UX system command given in the first argument.
No value is returned.
Is the return code from the last call to
Turns off trace globally and for any macros specified.
Macros specifically traced by can be untraced only by
specific calls to
With no arguments, turns on tracing for all macros
(including built-ins). Otherwise, turns on tracing
for named macros.
Transliterates the characters in its first argument
from the set given by the second argument to the set
given by the third. No abbreviations are permitted.
Removes the definition of the macro named in its argument.
Causes immediate output of text from diversions named as
arguments, or all diversions if no argument. Text
may be undiverted into another diversion. Undivert‐
ing discards the diverted text.
(XPG4 only.) It is an error to specify an argument containing any non-
numeric character for the built-in-macros: and
SEE ALSOcpp(1), ratfor(1).
STANDARDS CONFORMANCEm4(1)
