m4: Operation modes

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1 2.1 Command line options for operation modes
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1 Several options control the overall operation of 'm4':
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1 '--help'
1      Print a help summary on standard output, then immediately exit 'm4'
1      without reading any input files or performing any other actions.
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1 '--version'
1      Print the version number of the program on standard output, then
1      immediately exit 'm4' without reading any input files or performing
1      any other actions.
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1 '-E'
1 '--fatal-warnings'
1      Controls the effect of warnings.  If unspecified, then execution
1      continues and exit status is unaffected when a warning is printed.
1      If specified exactly once, warnings become fatal; when one is
1      issued, execution continues, but the exit status will be non-zero.
1      If specified multiple times, then execution halts with non-zero
1      status the first time a warning is issued.  The introduction of
1      behavior levels is new to M4 1.4.9; for behavior consistent with
1      earlier versions, you should specify '-E' twice.
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1 '-i'
1 '--interactive'
1 '-e'
1      Makes this invocation of 'm4' interactive.  This means that all
1      output will be unbuffered, and interrupts will be ignored.  The
1      spelling '-e' exists for compatibility with other 'm4'
1      implementations, and issues a warning because it may be withdrawn
1      in a future version of GNU M4.
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1 '-P'
1 '--prefix-builtins'
1      Internally modify _all_ builtin macro names so they all start with
1      the prefix 'm4_'.  For example, using this option, one should write
1      'm4_define' instead of 'define', and 'm4___file__' instead of
1      '__file__'.  This option has no effect if '-R' is also specified.
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1 '-Q'
1 '--quiet'
1 '--silent'
1      Suppress warnings, such as missing or superfluous arguments in
1      macro calls, or treating the empty string as zero.
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1 '--warn-macro-sequence[=REGEXP]'
1      Issue a warning if the regular expression REGEXP has a non-empty
1      match in any macro definition (either by 'define' or 'pushdef').
1      Empty matches are ignored; therefore, supplying the empty string as
1      REGEXP disables any warning.  If the optional REGEXP is not
1      supplied, then the default regular expression is
1      '\$\({[^}]*}\|[0-9][0-9]+\)' (a literal '$' followed by multiple
1      digits or by an open brace), since these sequences will change
1      semantics in the default operation of GNU M4 2.0 (due to a change
1      in how more than 9 arguments in a macro definition will be handled,
1      ⇒Arguments).  Providing an alternate regular expression can
1      provide a useful reverse lookup feature of finding where a macro is
1      defined to have a given definition.
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1 '-W REGEXP'
1 '--word-regexp=REGEXP'
1      Use REGEXP as an alternative syntax for macro names.  This
1      experimental option will not be present in all GNU 'm4'
1      implementations (⇒Changeword).
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