Re: Strange grep behavior

From: Adam Price (adam+usenet_at_pappnase.co.uk)
Date: 11/10/03

  • Next message: Dirk Munk: "Re: A book that explains what is better ultrix or vms." 
    Date: Mon, 10 Nov 2003 18:01:32 -0000

    In news:boo9co$cu4$1@gwdu112.gwdg.de,
    Helge Preuss <spam.preuss@fhi-berlin.mpg.de> typed:
    > Hi,
    > a colleague of mine complained to me that grep does not print
    > lines matching the search expression in some of his files, giving
    > the message "binary file foo.txt matches". Now his files are just
    > plain old text files. What is even stranger, if he renames that
    > file, grep prints the matching lines.
    > Now I was not able to reproduce this behavior, but I found a
    > different unexpected behavior: grepping for a string in a binary
    > file, which i know it exists, two times out of three (different
    > strings) it does not find the search string. The third time, it
    > just prints the string. No line number, no mention of a binary
    > file eiteher.
    > So my questions: Is this behavior known, maybe even documented?
    > More generally, how does grep determine whether a file is a
    > binary?
    > The OS in case is Tru64 5.1a.
    > TIA
    > Helge

    A file is binary if it contains 'non-printing' characters.
    If you look at the description section of the man page..
    http://h30097.www3.hp.com/docs/base_doc/DOCUMENTATION/V51A_HTML/MAN/MAN1/0170____.HTM
    You will see...

      [Tru64 UNIX] Running grep on a file that is not a text file (for example,
      an .o file) produces unpredictable results and is discouraged.

    So as you can see the results are unpredictable and discouraged.
    As for your colleagues files, have they been anywhere near a
    windows box?
    Are you sure they are plain text?
    If you view the files with cat -v do you see any strange things?

    Hope this helps some,
    Adam

  • Next message: Dirk Munk: "Re: A book that explains what is better ultrix or vms."

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