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Re: Fast forward-backward (write-read)

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On 23-Oct-2012 19:56, Tim Chase wrote:
> On 10/23/12 12:17, Virgil Stokes wrote:
>> On 23-Oct-2012 18:09, Tim Chase wrote:
>>>> Finally, to my question --- What is a fast way to write these
>>>> variables to an external file and then read them in
>>>> backwards?
>>> Am I missing something, or would the fairly-standard "tac"
>>> utility do the reversal you want?  It should[*] be optimized to
>>> handle on-disk files in a smart manner.
>> Not sure about "tac" --- could you provide more details on this
>> and/or a simple example of how it could be used for fast reversed
>> "reading" of a data file?
> Well, if you're reading input.txt (and assuming it's one record per
> line, separated by newlines), you can just use
>
>    tac < input.txt > backwards.txt
>
> which will create a secondary file that is the first file in reverse
> order.  Your program can then process this secondary file in-order
> (which would be backwards from your source).
>
> I might have misunderstood your difficulty, but it _sounded_ like
> you just want to inverse the order of a file.
Yes, I do wish to inverse the order,  but the "forward in time" file will be in 
binary.

--V

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Re: Fast forward-backward (write-read) Virgil Stokes <vs@it.uu.se> - 2012-10-23 20:37 +0200
  Re: Fast forward-backward (write-read) Paul Rubin <no.email@nospam.invalid> - 2012-10-23 16:46 -0700
    Re: Fast forward-backward (write-read) Dave Angel <d@davea.name> - 2012-10-28 07:18 -0400
    Re: Fast forward-backward (write-read) Virgil Stokes <vs@it.uu.se> - 2012-10-28 15:20 +0100
    Re: Fast forward-backward (write-read) Oscar Benjamin <oscar.j.benjamin@gmail.com> - 2012-10-28 18:21 +0000
    Re: Fast forward-backward (write-read) Virgil Stokes <vs@it.uu.se> - 2012-10-28 23:36 +0100

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