Annotation of src/usr.bin/m4/m4.1, Revision 1.18
1.18 ! espie 1: .\" @(#) $OpenBSD: m4.1,v 1.17 2000/07/06 04:06:55 aaron Exp $
1.1 deraadt 2: .\"
3: .\"
4: .Dd January 26, 1993
1.5 aaron 5: .Dt M4 1
1.1 deraadt 6: .Os
7: .Sh NAME
8: .Nm m4
9: .Nd macro language processor
10: .Sh SYNOPSIS
11: .Nm m4
1.12 espie 12: .Op Fl g
1.1 deraadt 13: .Oo
14: .Fl D Ns Ar name Ns Op Ar =value
15: .Oc
16: .Op Fl U Ns Ar name
1.7 espie 17: .Op Fl I Ar dirname
1.1 deraadt 18: .Sh DESCRIPTION
19: The
20: .Nm m4
21: utility is a macro processor that can be used as a front end to any
22: language (e.g., C, ratfor, fortran, lex, and yacc).
23: .Nm m4
24: reads from the standard input and writes
25: the processed text to the standard output.
26: .Pp
1.8 espie 27: Macro calls have the form name(argument1[, argument2, ..., argumentN]).
1.1 deraadt 28: .Pp
29: There cannot be any space following the macro name and the open
1.10 aaron 30: parenthesis
31: .Pq Ql ( .
32: If the macro name is not followed by an open
1.5 aaron 33: parenthesis it is processed with no arguments.
1.1 deraadt 34: .Pp
35: Macro names consist of a leading alphabetic or underscore
1.9 espie 36: possibly followed by alphanumeric or underscore characters, e.g.,
1.10 aaron 37: valid macro names match the pattern
38: .Dq [a-zA-Z_][a-zA-Z0-9_]* .
1.1 deraadt 39: .Pp
1.10 aaron 40: In arguments to macros, leading unquoted space, tab, and newline
41: .Pq Ql \en
42: characters are ignored.
43: To quote strings, use left and right single
44: quotes (e.g.,
45: .Sq \ this is a string with a leading space ) .
46: You can change the quote characters with the
1.5 aaron 47: .Ic changequote
48: built-in macro.
1.9 espie 49: .Pp
1.12 espie 50: Most built-ins don't make any sense without arguments, and hence are not
1.9 espie 51: recognized as special when not followed by an open parenthesis.
1.1 deraadt 52: .Pp
53: The options are as follows:
54: .Bl -tag -width "-Dname[=value]xxx"
55: .It Fl D Ns Ar name Ns Oo
56: .Ar =value
57: .Oc
58: Define the symbol
59: .Ar name
1.10 aaron 60: to have some value (or
61: .Dv NULL ) .
1.1 deraadt 62: .It Fl "U" Ns Ar "name"
63: Undefine the symbol
64: .Ar name .
1.7 espie 65: .It Fl I Ar "dirname"
1.15 aaron 66: Add directory
1.7 espie 67: .Ar dirname
68: to the include path.
1.12 espie 69: .It Fl g
1.13 aaron 70: Activate GNU-m4 compatibility mode.
1.15 aaron 71: In this mode, changequote with
1.12 espie 72: two empty parameters deactivates quotes, translit handles simple character
73: ranges (e.g., a-z) and regular expressions mimic emacs behavior.
1.17 aaron 74: .El
1.1 deraadt 75: .Sh SYNTAX
76: .Nm m4
1.10 aaron 77: provides the following built-in macros.
78: They may be redefined, losing their original meaning.
79: Return values are null unless otherwise stated.
1.1 deraadt 80: .Bl -tag -width changequotexxx
1.11 espie 81: .It Ic builtin
82: Calls a built-in by its name, overriding possible redefinitions.
1.5 aaron 83: .It Ic changecom
1.10 aaron 84: Change the start and end comment sequences.
85: The default is the pound sign
86: .Pq Ql #
87: and the newline character.
88: With no arguments comments are turned off.
89: The maximum length for a comment marker is five characters.
1.5 aaron 90: .It Ic changequote
1.1 deraadt 91: Defines the quote symbols to be the first and second arguments.
1.10 aaron 92: The symbols may be up to five characters long.
93: If no arguments are
1.1 deraadt 94: given it restores the default open and close single quotes.
1.5 aaron 95: .It Ic decr
1.10 aaron 96: Decrements the argument by 1.
97: The argument must be a valid numeric string.
1.5 aaron 98: .It Ic define
1.1 deraadt 99: Define a new macro named by the first argument to have the
1.10 aaron 100: value of the second argument.
101: Each occurrence of
102: .Ql $n
103: (where
104: .Ar n
105: is 0 through 9) is replaced by the
106: .Ar n Ns 'th
107: argument.
108: .Ql $0
109: is the name of the calling macro.
110: Undefined arguments are replaced by a null string.
111: .Ql $#
112: is replaced by the number of arguments;
113: .Ql $*
114: is replaced by all arguments comma separated;
115: .Ql $@
116: is the same as
117: .Ql $*
118: but all arguments are quoted against further expansion.
1.5 aaron 119: .It Ic defn
1.10 aaron 120: Returns the quoted definition for each argument.
121: This can be used to rename
1.1 deraadt 122: macro definitions (even for built-in macros).
1.5 aaron 123: .It Ic divert
1.1 deraadt 124: There are 10 output queues (numbered 0-9).
125: At the end of processing
126: .Nm m4
127: concatenates all the queues in numerical order to produce the
1.10 aaron 128: final output.
129: Initially the output queue is 0.
130: The divert
1.1 deraadt 131: macro allows you to select a new output queue (an invalid argument
132: passed to divert causes output to be discarded).
1.5 aaron 133: .It Ic divnum
1.1 deraadt 134: Returns the current output queue number.
1.5 aaron 135: .It Ic dnl
1.1 deraadt 136: Discard input characters up to and including the next newline.
1.5 aaron 137: .It Ic dumpdef
1.1 deraadt 138: Prints the names and definitions for the named items, or for everything
139: if no arguments are passed.
1.5 aaron 140: .It Ic errprint
1.1 deraadt 141: Prints the first argument on the standard error output stream.
1.18 ! espie 142: .It Ic esyscmd
! 143: Pass its first argument to a shell and returns the shell's standard output.
! 144: Note that the shell shares its standard input and standard error with
! 145: .Nm
1.5 aaron 146: .It Ic eval
1.1 deraadt 147: Computes the first argument as an arithmetic expression using 32-bit
1.10 aaron 148: arithmetic.
149: Operators are the standard C ternary, arithmetic, logical,
150: shift, relational, bitwise, and parentheses operators.
151: You can specify
152: octal, decimal, and hexadecimal numbers as in C.
153: The second argument (if any)
154: specifies the radix for the result and the third argument (if any)
155: specifies the minimum number of digits in the result.
1.5 aaron 156: .It Ic expr
157: This is an alias for
158: .Ic eval .
159: .It Ic ifdef
1.1 deraadt 160: If the macro named by the first argument is defined then return the second
1.10 aaron 161: argument, otherwise the third.
162: If there is no third argument, the value is
163: .Dv NULL .
164: The word
165: .Qq unix
166: is predefined.
1.5 aaron 167: .It Ic ifelse
168: If the first argument matches the second argument then
169: .Ic ifelse
170: returns
1.10 aaron 171: the third argument.
172: If the match fails the three arguments are
1.1 deraadt 173: discarded and the next three arguments are used until there is
1.10 aaron 174: zero or one arguments left, either this last argument or
175: .Dv NULL
176: is returned if no other matches were found.
1.5 aaron 177: .It Ic include
1.1 deraadt 178: Returns the contents of the file specified in the first argument.
1.7 espie 179: If the file is not found as is, look through the include path:
180: first the directories specified with
181: .Fl I
182: on the command line, then the environment variable
1.10 aaron 183: .Ev M4PATH ,
1.7 espie 184: as a colon-separated list of directories.
1.1 deraadt 185: Include aborts with an error message if the file cannot be included.
1.5 aaron 186: .It Ic incr
1.10 aaron 187: Increments the argument by 1.
188: The argument must be a valid numeric string.
1.5 aaron 189: .It Ic index
1.1 deraadt 190: Returns the index of the second argument in the first argument (e.g.,
1.10 aaron 191: .Ic index(the quick brown fox jumped, fox)
192: returns 16).
193: If the second
194: argument is not found index returns \-1.
1.11 espie 195: .It Ic indir
196: Indirectly calls the macro whose name is passed as the first arguments,
197: with the remaining arguments passed as first, ... arguments.
1.5 aaron 198: .It Ic len
1.10 aaron 199: Returns the number of characters in the first argument.
200: Extra arguments
1.1 deraadt 201: are ignored.
1.5 aaron 202: .It Ic m4exit
1.1 deraadt 203: Immediately exits with the return value specified by the first argument,
204: 0 if none.
1.5 aaron 205: .It Ic m4wrap
1.10 aaron 206: Allows you to define what happens at the final
207: .Dv EOF ,
208: usually for cleanup purposes (e.g.,
209: .Ic m4wrap("cleanup(tempfile)")
210: causes the macro cleanup to be
1.16 aaron 211: invoked after all other processing is done).
1.5 aaron 212: .It Ic maketemp
1.10 aaron 213: Translates the string
1.15 aaron 214: .Dq XXXXX
1.10 aaron 215: in the first argument with the current process
216: ID leaving other characters alone.
217: This can be used to create unique
1.1 deraadt 218: temporary file names.
1.5 aaron 219: .It Ic paste
1.1 deraadt 220: Includes the contents of the file specified by the first argument without
1.10 aaron 221: any macro processing.
222: Aborts with an error message if the file cannot be
1.1 deraadt 223: included.
1.11 espie 224: .It Ic patsubst
225: Substitutes a regular expression in a string with a replacement string.
226: Usual substitution patterns apply: an ampersand
1.15 aaron 227: .Pq Ql &
1.11 espie 228: is replaced by the string matching the regular expression.
229: The string
230: .Ql \e# ,
231: where
232: .Ql #
233: is a digit, is replaced by the corresponding back-reference.
1.5 aaron 234: .It Ic popdef
235: Restores the
236: .Ic pushdef Ns ed
237: definition for each argument.
238: .It Ic pushdef
239: Takes the same arguments as
240: .Ic define ,
241: but it saves the definition on a
242: stack for later retrieval by
243: .Ic popdef .
1.11 espie 244: .It Ic regexp
1.13 aaron 245: Finds a regular expression in a string.
246: If no further arguments are given,
1.14 aaron 247: it returns the first match position or \-1 if no match.
248: If a third argument
1.11 espie 249: is provided, it returns the replacement string, with sub-patterns replaced.
1.5 aaron 250: .It Ic shift
1.1 deraadt 251: Returns all but the first argument, the remaining arguments are
1.10 aaron 252: quoted and pushed back with commas in between.
253: The quoting
1.1 deraadt 254: nullifies the effect of the extra scan that will subsequently be
255: performed.
1.5 aaron 256: .It Ic sinclude
257: Similar to
258: .Ic include ,
259: except it ignores any errors.
260: .It Ic spaste
261: Similar to
262: .Ic paste ,
263: except it ignores any errors.
264: .It Ic substr
1.1 deraadt 265: Returns a substring of the first argument starting at the offset specified
266: by the second argument and the length specified by the third argument.
267: If no third argument is present it returns the rest of the string.
1.5 aaron 268: .It Ic syscmd
1.10 aaron 269: Passes the first argument to the shell.
270: Nothing is returned.
1.5 aaron 271: .It Ic sysval
272: Returns the return value from the last
273: .Ic syscmd .
274: .It Ic translit
1.1 deraadt 275: Transliterate the characters in the first argument from the set
1.10 aaron 276: given by the second argument to the set given by the third.
277: You cannot
1.1 deraadt 278: use
279: .Xr tr 1
280: style abbreviations.
1.5 aaron 281: .It Ic undefine
1.1 deraadt 282: Removes the definition for the macro specified by the first argument.
1.5 aaron 283: .It Ic undivert
1.1 deraadt 284: Flushes the named output queues (or all queues if no arguments).
1.5 aaron 285: .It Ic unix
1.1 deraadt 286: A pre-defined macro for testing the OS platform.
1.11 espie 287: .It Ic __line__
288: Returns the current file's line number.
289: .It Ic __file__
290: Returns the current file's name.
1.1 deraadt 291: .El
292: .Sh AUTHOR
1.11 espie 293: Ozan Yigit <oz@sis.yorku.ca> and Richard A. O'Keefe (ok@goanna.cs.rmit.OZ.AU).
294: GNU-m4 compatibility extensions by Marc Espie <espie@cvs.openbsd.org>.
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