coreutils: ptx invocation

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1 7.5 ‘ptx’: Produce permuted indexes
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1 ‘ptx’ reads a text file and essentially produces a permuted index, with
1 each keyword in its context.  The calling sketch is either one of:
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1      ptx [OPTION ...] [FILE ...]
1      ptx -G [OPTION ...] [INPUT [OUTPUT]]
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1    The ‘-G’ (or its equivalent: ‘--traditional’) option disables all GNU
1 extensions and reverts to traditional mode, thus introducing some
1 limitations and changing several of the program’s default option values.
1 When ‘-G’ is not specified, GNU extensions are always enabled.  GNU
1 extensions to ‘ptx’ are documented wherever appropriate in this
1 document.  ⇒Compatibility in ptx, for the full list.
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1    Individual options are explained in the following sections.
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1    When GNU extensions are enabled, there may be zero, one or several
1 FILEs after the options.  If there is no FILE, the program reads the
1 standard input.  If there is one or several FILEs, they give the name of
1 input files which are all read in turn, as if all the input files were
1 concatenated.  However, there is a full contextual break between each
1 file and, when automatic referencing is requested, file names and line
1 numbers refer to individual text input files.  In all cases, the program
1 outputs the permuted index to the standard output.
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1    When GNU extensions are _not_ enabled, that is, when the program
1 operates in traditional mode, there may be zero, one or two parameters
1 besides the options.  If there are no parameters, the program reads the
1 standard input and outputs the permuted index to the standard output.
1 If there is only one parameter, it names the text INPUT to be read
1 instead of the standard input.  If two parameters are given, they give
1 respectively the name of the INPUT file to read and the name of the
1 OUTPUT file to produce.  _Be very careful_ to note that, in this case,
1 the contents of file given by the second parameter is destroyed.  This
1 behavior is dictated by System V ‘ptx’ compatibility; GNU Standards
1 normally discourage output parameters not introduced by an option.
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1    Note that for _any_ file named as the value of an option or as an
1 input text file, a single dash ‘-’ may be used, in which case standard
1 input is assumed.  However, it would not make sense to use this
1 convention more than once per program invocation.
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Menu

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· General options in ptx      Options which affect general program behavior.
· Charset selection in ptx    Underlying character set considerations.
· Input processing in ptx     Input fields, contexts, and keyword selection.
· Output formatting in ptx    Types of output format, and sizing the fields.
· Compatibility in ptx
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