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M4(1) FreeBSD General Commands Manual M4(1) NAME m4 -- macro language processor SYNOPSIS m4 [-s] [-D name[=value]] [-U name] [file ...] DESCRIPTION The m4 utility is a macro processor that can be used as a front end to any language (e.g., C, ratfor, fortran, lex, and yacc). Each of the argument files is processed in order. If there are no files, or if a filename is `-', the standard input is read. The processed text is sent to the standard output. Macro calls have the form name(argument1[, argument2, ...,] argumentN). There cannot be any space following the macro name and the open parenthe- ses '('. If the macro name is not followed by an open parentheses it is processed with no arguments. Macro names consist of a leading alphabetic or underscore possibly fol- lowed by alphanumeric or underscore characters, therefore valid macro names match this pattern [a-zA-Z_][a-zA-Z0-9_]*. In arguments to macros, leading unquoted space, tab and newline charac- ters are ignored. To quote strings use left and right single quotes (e.g., ` this is a string with a leading space'). You can change the quote characters with the changequote built-in macro. The options are as follows: -s Emit #line directives for cpp(1). -D name[=value] Define the symbol name to have some value (or NULL). -U name Undefine the symbol name. SYNTAX m4 provides the following built-in macros. They may be redefined, losing their original meaning. Return values are NULL unless otherwise stated. changecom Change the start and end comment sequences. The default is the pound sign `#' and the newline character. With no arguments comments are turned off. The maximum length for a comment marker is five characters. changequote Defines the quote symbols to be the first and second arguments. Note, only the first character of each argu- ment is used. If no arguments are given it restores the default open and close single quotes. decr Decrements the argument by 1. The argument must be a valid numeric string. define Define a new macro named by the first argument to have the value of the second argument. Each occurrence of $n (where n is 0 through 9) is replaced by the n'th argu- ment. $0 is the name of the calling macro. Undefined arguments are replaced by a NULL string. $# is replaced by the number of arguments; $* is replaced by all argu- ments comma separated; $@ is the same as $* but all argu- ments are quoted against further expansion. defn Returns the quoted definition for each argument. This can be used to rename macro definitions (even for built- in macros). divert There are 10 output queues (numbered 0-9). At the end of processing m4 concatenates all the queues in numerical order to produce the final output. Initially the output queue is 0. The divert macro allows you to select a new output queue (an invalid argument passed to divert causes output to be discarded). divnum Returns the current output queue number. dnl Discard input characters up to and including the next newline. dumpdef Prints the names and definitions for the named items, or for everything if no arguments are passed. errprint Prints the first argument on the standard error output stream. eval Computes the first argument as an arithmetic expression using 32-bit arithmetic. Operators are the standard C ternary, arithmetic, logical, shift, relational, bitwise, and parentheses operators. You can specify octal, deci- mal, and hexadecimal numbers as in C. The second argu- ment (if any) specifies the radix for the result and the third argument (if any) specifies the minimum number of digits in the result. expr This is an alias for eval. ifdef If the macro named by the first argument is defined then return the second argument, otherwise the third. If there is no third argument, the value is NULL. The word `unix' is predefined. ifelse If the first argument matches the second argument then ifelse returns the third argument. If the match fails the three arguments are discarded and the next three arguments are used until there is zero or one arguments left, either this last argument or NULL is returned if no other matches were found. include Returns the contents of the file specified in the first argument. Include aborts with an error message if the file cannot be included. incr Increments the argument by 1. The argument must be a valid numeric string. index Returns the index of the second argument in the first argument (e.g., index(the quick brown fox jumped, fox) returns 16). If the second argument is not found index returns -1. len Returns the number of characters in the first argument. Extra arguments are ignored. m4exit Immediately exits with the return value specified by the first argument, 0 if none. m4wrap Allows you to define what happens at the final EOF, usu- ally for cleanup purposes (e.g., m4wrap("cleanup(temp- file)") causes the macro cleanup to be invoked after all other processing is done.) maketemp Translates the string XXXXX in the first argument with the current process ID leaving other characters alone. This can be used to create unique temporary file names. paste Includes the contents of the file specified by the first argument without any macro processing. Aborts with an error message if the file cannot be included. popdef Restores the pushdef'ed definition for each argument. pushdef Takes the same arguments as define, but it saves the def- inition on a stack for later retrieval by popdef. shift Returns all but the first argument, the remaining 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 Similar to include, except it ignores any errors. spaste Similar to paste, except it ignores any errors. substr Returns a substring of the first argument starting at the offset specified by the second argument and the length specified by the third argument. If no third argument is present it returns the rest of the string. syscmd Passes the first argument to the shell. Nothing is returned. sysval Returns the return value from the last syscmd. translit Transliterate the characters in the first argument from the set given by the second argument to the set given by the third. You cannot use tr(1) style abbreviations. undefine Removes the definition for the macro specified by the first argument. undivert Flushes the named output queues (or all queues if no arguments). unix A pre-defined macro for testing the OS platform. DIAGNOSTICS The m4 utility exits 0 on success, and >0 if an error occurs. The exit status can be specified by the input file using the m4exit macro. SEE ALSO cpp(1) STANDARDS The m4 utility is compatible with the IEEE Std 1003.1-2001 (``POSIX.1'') specification with the exception of the traceon and traceoff built-in macros, which are not implemented. The expr, paste, spaste and unix built-in macros are extensions to the standard. AUTHORS Ozan Yigit <oz@sis.yorku.ca> and Richard A. O'Keefe <ok@goanna.cs.rmit.OZ.AU> BUGS The tracing macros are not implemented. FreeBSD 11.1 January 26, 1993 FreeBSD 11.1
NAME | SYNOPSIS | DESCRIPTION | SYNTAX | DIAGNOSTICS | SEE ALSO | STANDARDS | AUTHORS | BUGS
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