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Re: Tail not reading to end of input
FWIW, a little non-Cygwin (VS2008) test app to display results from
fstat(0,...) returns the same thing on XP and Vista Ent SP1:
0x00002000 which means character special, and not regular.
On Tue, Apr 15, 2008 at 3:23 PM, smr xxxx <firstname.lastname@example.org> wrote:
> I've done some debugging of tail.exe on XP (which works) and Vista
> Enterprise SP1 (which doesn't), and so far have found two differences
> when tailing output piped from another program:
> 1. S_ISREG (stats.st_mode) returns 0 on XP, but 1 on Vista (I
> haven't yet determined if this is an Enterprise-only or an SP1-only
> 2. lseek() fails on XP, but succeeds on Vista. The SEEK_CUR below
> returns 0, and the SEEK_END consistently returns 4105 in my tests (for
> output that should be much longer, so presumably it's looking at a
> single buffer of data).
> Combines, this means that on XP the following code in tail.c results
> in pipe_lines being called (as expected), but on Vista file_lines is
> being called. Does any of this mean anything to anyone?
> /* Use file_lines only if FD refers to a regular file for
> which lseek (... SEEK_END) works. */
> if ( ! presume_input_pipe
> && S_ISREG (stats.st_mode)
> && (start_pos = lseek (fd, 0, SEEK_CUR)) != -1
> && start_pos < (end_pos = lseek (fd, 0, SEEK_END)))
> On Mon, Apr 14, 2008 at 10:56 AM, smr xxxx <email@example.com> wrote:
> > Hi, I've just rebuilt my machine and done a clean install of the
> > latest Cygwin, and am having a problem with tail. I'm wanting to know
> > whether this is a known issue before digging deeper. For other
> > reasons, I've rebuilt my machine clean twice this weekend and have had
> > this problem both times -- I also sourced the Cygwin files from two
> > different mirrors.
> > It's been a few months since I last installed Cygwin, and all I can
> > think of that has changed since then is:
> > 1. I have a newer version of Cygwin
> > 2. I'm now on Vista Enterprise (was Vista Ultimate)
> > 3. I'm now on an SP1 of Vista (was original RTM of Vista)
> > When running a command such as "dir /s /a cygwin | tail -2" (from C:\)
> > it displays:
> > 03/04/2008 10:32 PM 35 7zr
> > 07/19/2007 02:05 PM
> > This last line is the 29th line of output. Redirecting to a file
> > shows that there are 7 spaces at the end of this last line, and the
> > total output is 1028 bytes, or 1000 after running dos2unix.
> > Moving C:\cygwin to C:\x\cygwin (to force some extra characters into
> > the output of the above command, ie. the "x\") and rerunning shows
> > that it again stops at precisely the same place (7 spaces after the
> > time on the 29th line), but the output is now 1032 bytes, or 1004
> > after running dos2unix, due to the extra characters.
> > If I first redirect the output of the dir command to a file and tail
> > that then all is well. Even running "type filename | tail -2" works.
> > Also, if I dos2unix the stream inplace (ie. "dir /s /a cygwin |
> > dos2unix | tail -2") it works correctly. Note that I installed with
> > Unix file type (as always).
> > I just tried the same on \Windows, and it stops on the 26th line at a
> > position that seems to amount to 1124 bytes, or 1098 when dos2unix'd.
> > I'm guessing that this is a bigger problem that just tail (I could be
> > wrong), but "dir /s /a cygwin | wc -l" doesn't have any problems.
> > Has anyone seen this before?
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