184 lines
6.8 KiB
Groff
184 lines
6.8 KiB
Groff
.\"
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.\" @(#) $FreeBSD$
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.\"
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.Dd January 26, 1993
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.Dt M4 1
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.Os
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.Sh NAME
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.Nm m4
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.Nd macro language processor
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.Sh SYNOPSIS
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.Nm m4
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.Oo
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.Fl D Ns Ar name Ns Op Ar =value
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.Oc
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.Op Fl U Ns Ar name
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.Op Ar filename
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\|.\|.\|.
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.Sh DESCRIPTION
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The
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.Nm m4
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utility is a macro processor that can be used as a front end to any
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language (e.g., C, ratfor, fortran, lex, and yacc).
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Each of the argument files is processed in order.
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If there are no files, or if a filename is \`-\', the standard input is read.
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The processed text is sent to the standard output.
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.Pp
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Macro calls have the form name(argument1[, argument2, ...,] argumentN).
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.Pp
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There cannot be any space following the macro name and the open
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parentheses '('. If the macro name is not followed by an open
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parentheses it is processed with no arguments.
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.Pp
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Macro names consist of a leading alphabetic or underscore
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possibly followed by alphanumeric or underscore characters, therefore
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valid macro names match this pattern [a-zA-Z_][a-zA-Z0-9_]*.
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.Pp
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In arguments to macros, leading unquoted space, tab and newline
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characters are ignored. To quote strings use left and right single
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quotes (e.g., ` this is a string with a leading space'). You can change
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the quote characters with the changequote built-in macro.
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.Pp
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The options are as follows:
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.Bl -tag -width "-Dname[=value]xxx"
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.It Fl D Ns Ar name Ns Oo
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.Ar =value
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.Oc
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Define the symbol
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.Ar name
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to have some value (or NULL).
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.It Fl "U" Ns Ar "name"
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Undefine the symbol
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.Ar name .
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.El
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.Sh SYNTAX
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.Nm m4
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provides the following built-in macros. They may be
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redefined, losing their original meaning.
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Return values are NULL unless otherwise stated.
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.Bl -tag -width changequotexxx
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.It changecom
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Change the start and end comment sequences. The default is
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the pound sign `#' and the newline character. With no arguments
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comments are turned off. The maximum length for a comment marker is
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five characters.
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.It changequote
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Defines the quote symbols to be the first and second arguments.
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Note, only the first character of each argument is used. If no arguments are
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given it restores the default open and close single quotes.
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.It decr
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Decrements the argument by 1. The argument must be a valid numeric string.
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.It define
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Define a new macro named by the first argument to have the
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value of the second argument. Each occurrence of $n (where n
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is 0 through 9) is replaced by the n'th argument. $0 is the name
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of the calling macro. Undefined arguments are replaced by a
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NULL string. $# is replaced by the number of arguments; $*
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is replaced by all arguments comma separated; $@ is the same
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as $* but all arguments are quoted against further expansion.
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.It defn
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Returns the quoted definition for each argument. This can be used to rename
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macro definitions (even for built-in macros).
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.It divert
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There are 10 output queues (numbered 0-9).
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At the end of processing
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.Nm m4
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concatenates all the queues in numerical order to produce the
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final output. Initially the output queue is 0. The divert
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macro allows you to select a new output queue (an invalid argument
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passed to divert causes output to be discarded).
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.It divnum
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Returns the current output queue number.
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.It dnl
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Discard input characters up to and including the next newline.
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.It dumpdef
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Prints the names and definitions for the named items, or for everything
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if no arguments are passed.
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.It errprint
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Prints the first argument on the standard error output stream.
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.It eval
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Computes the first argument as an arithmetic expression using 32-bit
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arithmetic. Operators are the standard C ternary, arithmetic, logical,
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shift, relational, bitwise, and parentheses operators. You can specify
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octal, decimal, and hexadecimal numbers as in C. The second argument (if
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any) specifies the radix for the result and the third argument (if
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any) specifies the minimum number of digits in the result.
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.It expr
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This is an alias for eval.
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.It ifdef
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If the macro named by the first argument is defined then return the second
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argument, otherwise the third. If there is no third argument,
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the value is NULL. The word `unix' is predefined.
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.It ifelse
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If the first argument matches the second argument then ifelse returns
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the third argument. If the match fails the three arguments are
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discarded and the next three arguments are used until there is
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zero or one arguments left, either this last argument or NULL is
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returned if no other matches were found.
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.It include
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Returns the contents of the file specified in the first argument.
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Include aborts with an error message if the file cannot be included.
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.It incr
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Increments the argument by 1. The argument must be a valid numeric string.
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.It index
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Returns the index of the second argument in the first argument (e.g.,
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index(the quick brown fox jumped, fox) returns 16). If the second
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argument is not found index returns -1.
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.It len
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Returns the number of characters in the first argument. Extra arguments
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are ignored.
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.It m4exit
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Immediately exits with the return value specified by the first argument,
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0 if none.
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.It m4wrap
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Allows you to define what happens at the final EOF, usually for cleanup
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purposes (e.g., m4wrap("cleanup(tempfile)") causes the macro cleanup to be
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invoked after all other processing is done.)
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.It maketemp
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Translates the string XXXXX in the first argument with the current process
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ID leaving other characters alone. This can be used to create unique
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temporary file names.
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.It paste
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Includes the contents of the file specified by the first argument without
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any macro processing. Aborts with an error message if the file cannot be
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included.
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.It popdef
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Restores the pushdef'ed definition for each argument.
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.It pushdef
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Takes the same arguments as define, but it saves the definition on a
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stack for later retrieval by popdef.
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.It shift
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Returns all but the first argument, the remaining arguments are
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quoted and pushed back with commas in between. The quoting
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nullifies the effect of the extra scan that will subsequently be
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performed.
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.It sinclude
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Similar to include, except it ignores any errors.
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.It spaste
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Similar to paste, except it ignores any errors.
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.It substr
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Returns a substring of the first argument starting at the offset specified
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by the second argument and the length specified by the third argument.
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If no third argument is present it returns the rest of the string.
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.It syscmd
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Passes the first argument to the shell. Nothing is returned.
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.It sysval
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Returns the return value from the last syscmd.
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.It translit
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Transliterate the characters in the first argument from the set
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given by the second argument to the set given by the third. You cannot
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use
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.Xr tr 1
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style abbreviations.
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.It undefine
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Removes the definition for the macro specified by the first argument.
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.It undivert
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Flushes the named output queues (or all queues if no arguments).
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.It unix
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A pre-defined macro for testing the OS platform.
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.El
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.Sh AUTHORS
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.An Ozan Yigit Aq oz@sis.yorku.ca
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and
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.An Richard A. O'Keefe Aq ok@goanna.cs.rmit.OZ.AU
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