Mailing list search didn't find this, nor does it appear in the FAQ... hopefully this isn't old news to all of you.
Files read from a pipe are treated differently by grep than files read directly. This results in some unexpected (by me) behaviour when using grep on files which use the a DOS line-end (cr/nl). This looks like a bug to me. I'd expect the following commands to have equivalent results: grep myregex blah grep myregex < blah cat blah | grep myregex They are equivalent when the regular file blah uses Unix line ends, but they differ for a file blahdos which uses DOS line ends. It appears to me as though grep is treating its input as binary when reading from a pipe, but correctly using "undossify_input()" in other cases. Here is an example. I've created two files, blah (nl line-end) and blahdos (cr/nl line-end). $ cat blah foobarTest $ od -Ax -a blah 000000 f o o b a r T e s t nl 00000b $ od -Ax -a blahdos 000000 f o o b a r T e s t cr nl 00000c These files should match the regex 'Test$' in all cases, but grep on blahdos fails for this case: $ cat blahdos | grep 'Test$' $ And here's why (not the -v to invert the match so we have something to look at): $ cat blahdos | grep -v 'Test$' | od -Ax -a 000000 f o o b a r T e s t cr nl 00000c There's still a cr/nl on the output which wouldn't be there if grep had interpreted its input as having DOS line ends. Here's what a successful grep of the UNIX line end file looks like: $ cat blah | grep 'Test$' | od -Ax -a 000000 f o o b a r T e s t nl 00000b In fact, if I read the blahdos file in any other way except through a pipe, it successfully matches (note the stripped out cr on the output): $ grep 'Test$' blahdos | od -Ax -a 000000 f o o b a r T e s t nl 00000b $ grep 'Test$' < blahdos | od -Ax -a 000000 f o o b a r T e s t nl 00000b Just in case you might think that this has something to do with cat (I did), here's the output of cat for each file: $ cat blah | od -Ax -a 000000 f o o b a r T e s t nl 00000b $ cat blahdos | od -Ax -a 000000 f o o b a r T e s t cr nl 00000c Using head instead of cat gives the same results as well, just to completely remove cat from the picture. I'm currently running these versions of tools on win2k: cygwin 1.3.18-1 textutils 2.0.21 (cat, od, head) grep 2.5 bash 2.05b.0(8)-release I also tried this out with cygwin 1.3.17-1 with identical results. If you need any further information, please cc me directly since I don't read the mailing lists very often. Stacey. -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Bug reporting: http://cygwin.com/bugs.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
