Manual page for M4(1V)
m4 - macro language processor
SYNOPSIS
m4
[
filename
] ...
SYSTEM V SYNOPSIS
/usr/5bin/m4
[
-es
]
[
-Bint
]
[
-Hint
]
[
-Sint
]
[
-Tint
]
[
-Dname=val
]
[
-Uname
]
[
filename
]...
AVAILABILITY
The System V version of this command is available with the
System V
software installation option.
Refer to
[a manual with the abbreviation INSTALL]
for information on how to install optional software.
DESCRIPTION
m4
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
`-',
the standard input is read.
The processed text is written on the standard output.
Macro calls have the form:
-
name(argument1[,
argument2,
...,]
argumentn)
The
`('
must immediately follow the name of the macro.
If the name of a defined macro is not followed by a
`(',
it is interpreted as a call of the macro with no arguments.
Potential macro names consist of letters, digits, and
`_',
(underscores)
where the first character is not a digit.
Leading unquoted
SPACE,
TAB,
and
NEWLINE
characters are ignored while collecting arguments.
Left and right single quotes
(`')
are used to quote strings.
The value of a quoted string is the string stripped of the quotes.
When a macro name is recognized,
the arguments are collected by searching
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.
SYSTEM V OPTIONS
The options and their effects are as follows:
- -e
-
Operate interactively.
Interrupts are ignored and the output is unbuffered.
- -s
-
Enable line sync output for the C preprocessor
(#line ...)
- -Bint
-
Change the size of the push-back and argument collection
buffers from the default of 4,096.
- -Hint
-
Change the size of the symbol table hash array from the
default of 199.
The size should be prime.
- -Sint
-
Change the size of the call stack from the default of 100 slots.
Macros take three slots, and non-macro arguments take one.
- -Tint
-
Change the size of the token buffer from the default of 512 bytes.
To be effective, these flags must appear before any
file names and before any
-D
or
-U
flags:
- -Dname[=val]
-
Define
filename
to be
val
or to be
NULL
in
val's
absence.
- -Uname
-
Undefine
name.
USAGE
Built-In Macros
m4
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 arguments are replaced by the
NULL
string.
- undefine
-
Remove the definition of the macro named in the argument.
- 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
unix
is predefined.
- changequote
-
Change quote characters to the first and second arguments.
changequote
without arguments restores the original values (that is,
`').
- divert
-
m4
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
divert
macro changes the current output stream to
the (digit-string) argument.
Output diverted to a stream other than 0 through 9 is discarded.
- undivert
-
Display immediate output of text from diversions named as
arguments, or all diversions if no argument.
Text may be undiverted into another diversion.
Undiverting discards the diverted text.
- divnum
-
Return the value of the current output stream.
- dnl
-
Read and discard characters up to and including the next
NEWLINE.
- ifelse
-
Has three or more arguments.
If the first argument 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, 7 and so on.
Otherwise, the value is either the last string not used by the above
process, or, if it is not present,
NULL.
- incr
-
Return the value of the argument incremented by 1.
The value of the argument is calculated
by interpreting an initial digit-string as a decimal number.
- eval
-
Evaluate the argument as an arithmetic expression, using 32-bit arithmetic.
Operators include
+,
-,
*,
/,
%,
^
(exponentiation); relationals; parentheses.
- len
-
Return the number of characters in the argument.
- index
-
Return the position in the first argument where the second argument
begins (zero origin), or -1 if the second argument does not occur.
- substr
-
Return a substring of the 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
-
Transliterate the characters in the first argument
from the set given by the second argument
to the set given by the third.
No abbreviations are permitted.
- include
-
Return the contents of the file named in the argument.
- sinclude
-
Is similar to
include,
except that it says nothing if the file is inaccessible.
- syscmd
-
Execute the
system command given in the first argument.
No value is returned.
- maketemp
-
Fill in a string of
XXXXX
in the argument with the current process
ID.
- errprint
-
Print the argument on the diagnostic output file.
- dumpdef
-
Print current names and definitions,
for the named items, or for all if no arguments are given.
SYSTEM V USAGE
In the System V version of
m4,
the following built-in macros have added capabilities.
Built-In Macros
- define
-
`$#'
is replaced by the number of arguments;
$*
is replaced by a list of all the arguments separated by commas;
$@
is like
`$*',
but each argument is quoted (with the current quotes).
- changequote
-
Change quote symbols to the first and second arguments.
The symbols may be up to five characters long.
- eval
-
Additional operators include
bitwise
`&',
`|',
`^'
and
`~'.
Octal, decimal and hex numbers 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.
The System V version of
m4
makes available the following additional built-in macros.
- defn
-
Return the quoted definition of the argument(s).
It is useful for renaming macros, especially built-ins.
- pushdef
-
Like
define,
but saves any previous definition.
- popdef
-
Remove current definition of the argument(s),
exposing the previous one, if any.
- shift
-
Return 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
will subsequently be performed.
- changecom
-
Change left and right comment markers from the default
#
and
NEWLINE.
With no arguments, the comment mechanism 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.
- decr
-
Return the value of the argument decremented by 1.
- sysval
-
Return code from the last call to
syscmd.
- m4exit
-
Exit immediately from
m4.
Argument 1, if given, is the exit code;
the default is 0.
- m4wrap
-
Argument 1 will be pushed back at final
EOF.
For example,
`m4wrap(``cleanup()'')'.
- traceon
-
With no arguments, turn on tracing for all macros
(including built-ins).
Otherwise, turn on tracing for named macros.
- traceoff
-
Turn off trace globally and for any macros specified.
Macros specifically traced by
traceon
can be untraced only by specific calls to
traceoff.
SEE ALSO
cc.1v
m4 -- A Macro Processor,
in
[a manual with the abbreviation PUL]
NOTES
While the compiler allows 8-bit strings and comments,
8-bits are not allowed
anywhere else.
The
cc.1v
command does not generate or support 8-bit symbol names
because, until
ANSI C,
non-ASCII
support was not expected.
The
ANSI C
specification now suggests that string literals
and comments can contain any characters from any
character code set.
Created by unroff & hp-tools.
© somebody (See intro for details). All Rights Reserved.
Last modified 11/5/97