m4(1)
NAME
m4 - macro processor
SYNOPSIS
/usr/ccs/bin/m4 [-e] [-s] [-B int] [-H int] [-S int] [-
T int] [ -Dname [=val]] ... [-U name] ... [file...]
/usr/xpg4/bin/m4 [-e] [-s] [-B int] [-H int] [-S int] [-
T int] [ -Dname [ ...=val]] [-U name] ... [file...]
DESCRIPTION
The m4 utility is a macro processor intended as a front end
for C, assembler, and other languages. Each of the argument
files is processed in order; if there are no files, or if a
file is -, the standard input is read. The processed text is
written on the standard output.
Macro Syntax
Macro calls have the form:
name(arg1,arg2, ..., argn)
The open parenthesis character ( 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
alphanumeric characters and underscore (_), where the first
character is not a digit.
Leading unquoted blanks, <TAB>s, and NEWLINEs 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.
Macro Processing
When a macro name is recognized, its 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 that 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.
OPTIONS
The options and their effects are as follows:
-Bint Changes the size of the push-back and argument collec-
tion buffers from the default of 4,096.
-e Operates interactively. Interrupts are ignored and the
output is unbuffered.
-Hint Changes the size of the symbol table hash array from
the default of 199. The size should be prime.
-s Enables line sync output for the C preprocessor (#line
...)
-Sint Changes the size of the call stack from the default of
100slots. Macros take three slots, and non-macro argu-
ments take one.
-Tint Changes the size of the token buffer from the default
of 512bytes.
To be effective, the above flags must appear before any file
names and before any -D or -U flags:
-D name[=val]
Defines name to val or to NULL in val's absence.
-Uname
Undefines name.
OPERANDS
The following operand is supported:
file A path name of a text file to be processed. If no file
is given, or if it is -, the standard input is read.
USAGE
The m4 utility makes available the following built-in mac-
ros. These macros may be redefined, but once this is done
the original meaning is lost. Their values are NULL unless
otherwise stated.
changequote
Change quote symbols to the first and second argu-
ments. The symbols may be up to five characters long.
changequote without arguments restores the original
values (that is, `').
changecom
Change left and right comment markers from the default
# and NEWLINE. With no arguments, the comment mechan-
ism 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 Returns the value of its argument decremented by 1.
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; $# is replaced by the number of
arguments; $* is replaced by a list of all the argu-
ments separated by commas; $@ is like $*, but each
argument is quoted (with the current quotes).
defn Returns the quoted definition of its argument(s). It
is useful for renaming macros, especially built-ins.
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 its (digit-string) argument. Output diverted
to a stream other than 0 through 9 is discarded.
divnum
Returns the value of the current output stream.
dnl Reads and discards characters up to and including the
next NEWLINE.
dumpdef
Prints current names and definitions, for the named
items, or for all if no arguments are given.
errprint
Prints its argument on the diagnostic output file.
/usr/ccs/bin/m4
eval Evaluates its argument as an arithmetic expression,
using 32-bit signed-integer arithmetic. The following
operators are supported: parentheses, unary -, unary
+, !, ~, *, /, %, +, -, relationals, bitwise &, |, &&,
and ||. Octal 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.
/usr/xpg4/bin/m4
eval Evaluates its argument as an arithmetic expression,
using 32-bit signed-integer arithmetic. The following
operators are supported: parentheses, unary -, unary
+, !, ~, *, /, %, +, -, <<, >>, relationals, bitwise
&, |, &&, and ||. Precedence and associativity are as
in C. Octal and hex numbers may also 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.
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.
ifelse
This macro 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 and 7. Otherwise, the value is
either the fourth string, or, if it is not present,
NULL.
include
Returns the contents of the file named in the argu-
ment.
incr 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.
index Returns the position in its first argument where the
second argument begins (zero origin), or -1 if the
second argument does not occur.
len Returns the number of characters in its argument.
m4exit
This macro causes immediate exit from m4. Argument 1,
if given, is the exit code; the default is 0.
m4wrap
Argument 1 will be pushed back at final EOF. Example:
m4wrap(`cleanup()')
maketemp
Fills in a string of "X" characters in its argument
with the current process ID.
popdef
Removes current definition of its argument(s), expos-
ing the previous one, if any.
pushdef
Like define, but saves any previous definition.
shift Returns all but its first argument. The other argu-
ments are quoted and pushed back with commas in
between. The quoting nullifies the effect of the extra
scan that will subsequently be performed.
sinclude
This macro is identical to include, except that it
says nothing if the file is inaccessible.
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.
syscmd
This macro executes the command given in the first
argument. No value is returned.
sysval
This macro is the return code from the last call to
syscmd.
translit
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.
traceon
This macro with no arguments, turns on tracing for all
macros (including built-ins). Otherwise, turns on
tracing for named macros.
traceoff
Turns off trace globally and for any macros specified.
Macros specifically traced by traceon can be untraced
only by specific calls to traceoff.
undefine
Removes the definition of the macro named in its argu-
ment.
undivert
This macro causes immediate output of text from diver-
sions named as arguments, or all diversions if no
argument. Text may be undiverted into another diver-
sion. Undiverting discards the diverted text.
EXAMPLES
Example 1: Examples of m4 files
An example of a single m4 input file capable of generating
two output files follows. The file file1.m4 could contain
lines such as:
if(VER, 1, do_something)
if(VER, 2, do_something)
The makefile for the program might include:
file1.1.c : file1.m4
m4 -D VER=1 file1.m4 > file1.1.c
...
file1.2.c : file1.m4
m4 -D VER=2 file1.m4 > file1.2.c
...
The -U option can be used to undefine VER. If file1.m4 con-
tains:
if(VER, 1, do_something)
if(VER, 2, do_something)
ifndef(VER, do_something)
then the makefile would contain:
file1.0.c : file1.m4
m4 -U VER file1.m4 > file1.0.c
...
file1.1.c : file1.m4
m4 -D VER=1 file1.m4 > file1.1.c
...
file1.2.c : file1.m4
m4 -D VER=2 file1.m4 > file1.2.c
...
ENVIRONMENT VARIABLES
See environ(5) for descriptions of the following environment
variables that affect the execution of m4: LANG, LC_ALL,
LC_CTYPE, LC_MESSAGES, and NLSPATH.
EXIT STATUS
The following exit values are returned:
0 Successful completion.
>0 An error occurred
If the m4exit macro is used, the exit value can be specified
by the input file.
ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
/usr/ccs/bin/m4
____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Availability | SUNWcsu |
|_____________________________|_____________________________|
/usr/xpg4/bin/m4
____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Availability | SUNWxcu4 |
|_____________________________|_____________________________|
| Interface Stability | Standard |
|_____________________________|_____________________________|
SEE ALSO
as(1), attributes(5), environ(5), standards(5)
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