File: m4.info,  Node: Operation modes,  Next: Preprocessor features,  Up: Invoking m4

2.1 Command line options for operation modes
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Several options control the overall operation of ‘m4’:

‘--help’
     Print a help summary on standard output, then immediately exit ‘m4’
     without reading any input files or performing any other actions.

‘--version’
     Print the version number of the program on standard output, then
     immediately exit ‘m4’ without reading any input files or performing
     any other actions.

‘-E’
‘--fatal-warnings’
     Controls the effect of warnings.  If unspecified, then execution
     continues and exit status is unaffected when a warning is printed.
     If specified exactly once, warnings become fatal; when one is
     issued, execution continues, but the exit status will be non-zero.
     If specified multiple times, then execution halts with non-zero
     status the first time a warning is issued.  The introduction of
     behavior levels is new to M4 1.4.9; for behavior consistent with
     earlier versions, you should specify ‘-E’ twice.

‘-i’
‘--interactive’
‘-e’
     Makes this invocation of ‘m4’ interactive.  This means that all
     output will be unbuffered, and interrupts will be ignored.  The
     spelling ‘-e’ exists for compatibility with other ‘m4’
     implementations, and issues a warning because it may be withdrawn
     in a future version of GNU M4.

‘-P’
‘--prefix-builtins’
     Internally modify _all_ builtin macro names so they all start with
     the prefix ‘m4_’.  For example, using this option, one should write
     ‘m4_define’ instead of ‘define’, and ‘m4___file__’ instead of
     ‘__file__’.  This option has no effect if ‘-R’ is also specified.

‘-Q’
‘--quiet’
‘--silent’
     Suppress warnings, such as missing or superfluous arguments in
     macro calls, or treating the empty string as zero.

‘--warn-macro-sequence[=REGEXP]’
     Issue a warning if the regular expression REGEXP has a non-empty
     match in any macro definition (either by ‘define’ or ‘pushdef’).
     Empty matches are ignored; therefore, supplying the empty string as
     REGEXP disables any warning.  If the optional REGEXP is not
     supplied, then the default regular expression is
     ‘\$\({[^}]*}\|[0-9][0-9]+\)’ (a literal ‘$’ followed by multiple
     digits or by an open brace), since these sequences will change
     semantics in the default operation of GNU M4 2.0 (due to a change
     in how more than 9 arguments in a macro definition will be handled,
     *note Arguments::).  Providing an alternate regular expression can
     provide a useful reverse lookup feature of finding where a macro is
     defined to have a given definition.

‘-W REGEXP’
‘--word-regexp=REGEXP’
     Use REGEXP as an alternative syntax for macro names.  This
     experimental option will not be present in all GNU ‘m4’
     implementations (*note Changeword::).