bop has asked for the wisdom of the Perl Monks concerning the following question:

Hi Perl Monks,

I'm trying to sort a large file using the cygwin sort (so maybe this question should be rather addressed to a cygwin forum, but I don't actually think that it is a cygwin problem). As the file is much larger than can fit in memory, I set the directory where cygwin should store any sorted runs temporarily. As I like to keep my tmp directory small (I think /tmp is just a waste of space in most cases), I typically set that directory to `pwd`. This works for the cygwin internal version of perl: 
$ perl -e 'system "sort -T `pwd` --buffer-size=10 ../somefile.txt"' | 
+head

[download]
But fails for an external installation of perl (I also tried the external 32 bit version, which fails just the same): 
$ /cygdrive/c/Perl64/bin/perl -e 'system "sort -T `pwd` --buffer-size=
+10 ../somefile.txt"' | head
sort: cannot create temporary file: `pwd`/sort1JB3UE: No such file or 
+directory

[download]
The perl versions are: 
$ perl --version

This is perl, v5.8.8 built for cygwin-thread-multi-64int
(with 8 registered patches, see perl -V for more detail)

Copyright 1987-2006, Larry Wall

Perl may be copied only under the terms of either the Artistic License
+ or the
GNU General Public License, which may be found in the Perl 5 source ki
+t.

Complete documentation for Perl, including FAQ lists, should be found 
+on
this system using "man perl" or "perldoc perl".  If you have access to
+ the
Internet, point your browser at http://www.perl.org/, the Perl Home Pa
+ge.


$ /cygdrive/c/Perl64/bin/perl --version

This is perl, v5.10.0 built for MSWin32-x64-multi-thread
(with 3 registered patches, see perl -V for more detail)

Copyright 1987-2007, Larry Wall

Binary build 1002 [283697] provided by ActiveState http://www.ActiveSt
+ate.com
Built Jan 10 2008 10:53:05

Perl may be copied only under the terms of either the Artistic License
+ or the
GNU General Public License, which may be found in the Perl 5 source ki
+t.

Complete documentation for Perl, including FAQ lists, should be found 
+on
this system using "man perl" or "perldoc perl".  If you have access to
+ the
Internet, point your browser at http://www.perl.org/, the Perl Home Pa
+ge.

[download]
Any explanation and/or work arounds (other than increasing /tmp) would be much apcodeciated!
Thank you,
bop

Replies are listed 'Best First'.
Re: sort system call problem with activestate perl
by Anonymous Monk on Jul 03, 2008 at 13:17 UTC
    in windows, the default shell is cmd.exe, in cygwin its bash or csh or ...
[reply]
      To elaborate a bit more: Windows handles `pwd` as a literal. Since it can't create a file in the directory `pwd` (because it doesn't exist), it fails.

      One workaround is to use Cwd to obtain the current working dir in a platform-independent way.

[reply]
[d/l]
[select]
        Thank you Moritz,

        that makes sense. However, I don't really know how I can call Cwd from cygwin ("command not found" - I must have a thick day), but this works, working around the string literal issue: 
        perl -e 'my $path = `pwd`; system "sort -T " . $path . " --buffer-size=10 ../somefile.txt"'
        thank you,
        bop

        PS: I forgot to mention previously that I use such a small buffer size in order to recreate the problem I had (but I'm sure you guessed that).
[reply]
Re: sort system call problem with activestate perl
by starbolin (Hermit) on Jul 04, 2008 at 04:44 UTC

    An ethereal Anonymous Monk asides:

    "(I think /tmp is just a waste of space in most cases)"
    I "most" cases /tmp is mounted from it's own partition and therefor has it's own set of buffers. This is considered by some to be a good thing.

    s//----->\t/;$~="JAPH";s//\r<$~~/;{s|~$~-|-~$~|||s |-$~~|$~~-|||s,<$~~,<~$~,,s,~$~>,$~~>,, $|=1,select$,,$,,$,,1e-1;print;redo}
[reply]
[d/l]

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