more uses for mode 000 (will be: cat -v considered harmful)

[Steve Summit]

In article <1991Feb16.083327.13256 at metapro.DIALix.oz.au> bernie at metapro.DIALix.oz.au (Bernd Felsche) writes:
>In <1991Feb12.043341.29652 at athena.mit.edu> scs at adam.mit.edu (Steve Summit) writes:
>>The right way to exclude files matching some pattern is
>
>>	tar c `find . -print | grep -v pattern`
>
>>Now, Unix is far less restrictive than most operating systems on
>>things like command line length limitations, but this is one case
>>where you can overload even the generous allotments that the
>>shells (and exec) give you.  Therefore, a wrinkle that *is* a
>>worthwhile addition to tar is a way to read a list of filenames
>>from a file, or from standard input.
>
>A permanent fix would be to have a dynamically-sized u_area, or
>whatever it's called now. The arg list could then be stored in it, no
>matter how large it gets (within address space limitations). This
>means that commands don't have to read stdin or files for filenames,
>or whatever.

I'd hate to sound like an apologist for fixed-size arrays,
because I generally try to stamp them out whenever possible.
However, a way for tar to read filenames from a file or stream is
still important, because its uses are such that those address
space limitations could actually burn you in practice.  I have
selectively written tapes with tens of kilobytes of filenames
alone, which wouldn't have been possible on a pdp11 (or other
16-bit, 64K address space machine).

                                            Steve Summit
                                            scs at adam.mit.edu