Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!snorkelwacker.mit.edu!bloom-picayune.mit.edu!news From: scs@adam.mit.edu (Steve Summit) Newsgroups: comp.unix.internals Subject: Re: more uses for mode 000 (will be: cat -v considered harmful) Message-ID: <1991Feb24.002455.18029@athena.mit.edu> Date: 24 Feb 91 00:24:55 GMT References: <1991Feb12.043341.29652@athena.mit.edu> <1991Feb16.083327.13256@metapro.DIALix.oz.au> Sender: news@athena.mit.edu (News system) Reply-To: scs@adam.mit.edu Organization: Thermal Technologies, Inc. Lines: 30 In article <1991Feb16.083327.13256@metapro.DIALix.oz.au> bernie@metapro.DIALix.oz.au (Bernd Felsche) writes: >In <1991Feb12.043341.29652@athena.mit.edu> scs@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@adam.mit.edu Brought to you by Super Global Mega Corp .com