Re: Use tar to append?

[Cameron Simpson <cs@xxxxxxxxxx>]

On 09Mar2007 16:13, Mike McCarty <Mike.McCarty@xxxxxxxxxxxxx> wrote:
| Cameron Simpson wrote:
| >| (2) I don't
| >| want a detailed report, I want a progress report so I can know
| >| approx. how much has been done.
| >Which is why I suggested you do something other than "cat", like "grep".
| >You post process the tvf output as you see fit.
| 
| Ok. Makes sense. I'll need to learn a little more shell syntax
| to do that.

You want this:

  while read -r perm own size date time path
  do
    case "$path" in
      your-interesting-paths...)
        echo "$path" | wall
        ;;
    esac
  done

or something like it.

| >The other way, which is a little harder, is to run a "tar cvf" and post
| >process its output as it goes. Have a look at "entar", a script of mine 
| >which
| >does exactly that:
| >  http://www.cskk.ezoshosting.com/cs/css/bin/entar
| 
| Thanks, I'll have a look.

Ok. Note you won't need cs::Misc or cs::Upd for your needs (though they
are in the cs/ subdir of that folder). Rip 'em out and do what you want.

I have also thought of a much simpler way to solve your problem.

The trailer record is the source of all our pain. Write a small perl or
python or C program that seeks to the end of stdout minus the length of
the trailer record then execs a "tar cf - ..." for you. Thus:

  echo "first-directory" | wall
  tar cf tarfile first-directory
  for toplevel in the-other-directories
  do
    echo "$toplevel" | wall
    tarbackseek tarfile "$toplevel" 
  done

and make tarbackseek do something like this:

  main(int argc, char *argv[])
  { int tarfd=open(argv[1],"w+");
    close(1);
    dup(tarf,1);
    close(tarfd);
    lseek(1,SEEK_END,-512);
    execvp("tar","cf","-",argv[2],NULL);
  }

That C code is approximate and lacking headers, and I need to verify
that the trailer record is 512 bytes (it should be), but you get the
idea I'm sure.

I need to go out, can hack in detail later.

Cheers,
-- 
Cameron Simpson <cs@xxxxxxxxxx> DoD#743
http://www.cskk.ezoshosting.com/cs/

I knew I was a real biker when I pulled up beside a car at a stoplight and
the people inside locked all the doors.