Re: seekable pipes

>$ command_to_manage_seekable_stdout | seek-in [--] 
>command_to_use_seekable_stdin

I think that's a great idea.  Of course, I'd like to see a program more 
general than this example demonstrates:  one that negotiates general file 
semantics for both Standard Input and Standard Output.

Now do you have an idea for the process substitution case?
I.e. command_to_use_seekable_named_file <(command_to_implement_file) .

There are probably more examples where that's needed than where the | 
thing is needed, because I think the programs that expect advanced 
functions such as seek from files tend to open the files themselves, as 
opposed to getting them pre-opened as stdin or stdout.  E.g. editors.

>An optional time-out might prevent an infinite wait 
>if the first command never converted the pipe.

That would be out of place.  The concept of giving up on something because 
it's taken too much wall clock time is quite complex and not specific to 
setting up of seekable pipes, so should be done at a higher level. SIGALRM 
is good for that.

--
Bryan Henderson                               San Jose California
IBM Almaden Research Center                   Filesystems
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