06-03-2011
gzip vs pipe gzip: produce different file size
Hi All,
I have a random test file: test.txt, size: 146
$ ll test.txt
$ 146 test.txt
Take 1:
$ cat test.txt | gzip > test.txt.gz
$ ll test.txt.gz
$ 124 test.txt.gz
Take 2:
$ gzip test.txt
$ ll test.txt.gz
$ 133 test.txt.gz
As you can see, gzipping a file and piping into gzip produce different sized *gz files. The problem currently is that some archivers, such as WinZip and Cygwin's gunzip have to unzip the piped gzip file twice before it can be read as a plain text file. Why is this and how can I ensure piping into gzip produces the same file as gzipping a file?
Thanks,
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LEARN ABOUT DEBIAN
test::lectrotest::regressiontesting
Test::LectroTest::RegressionTesting(3pm) User Contributed Perl Documentation Test::LectroTest::RegressionTesting(3pm)
NAME
Test::LectroTest::RegressionTesting - How to do regression testing (for free!)
SYNOPSIS
use Test::LectroTest
regressions => "regressions.txt";
# -- OR --
use Test::LectroTest
playback_failures => "regression_suite_for_my_module.txt",
record_failures => "failures_in_the_field.txt";
# -- OR --
use Test::LectroTest::Compat
regressions => "regressions.txt";
# -- OR --
use Test::LectroTest::Compat
playback_failures => "regression_suite_for_my_module.txt",
record_failures => "failures_in_the_field.txt";
DESCRIPTION
Say that LectroTest uncovers a bug in your software by finding a random test case that proves one of your properties to be false. If you
apply a fix for the bug, how can you be sure that LectroTest will re-test the property using the exact same test case that "broke" it
before, just to be certain the bug really is fixed? And how can you be sure that future changes to your code will not reintroduce the same
bug without your knowing it?
For situations like these, LectroTest can record failure-causing test cases to a file, and it can play those test cases back as part of its
normal testing strategy.
The easiest way to take advantage of this feature is to set the regressions parameter when you "use" Test::LectroTest or
Test::LectroTest::Compat:
use Test::LectroTest
regressions => "regressions.txt";
This tells LectroTest to use the file "regressions.txt" for both recording and playing back failures. If you want to record and play back
from separate files, use the record_failures and playback_failures options:
use Test::LectroTest::Compat
playback_failures => "regression_suite_for_my_module.txt",
record_failures => "failures_in_the_field.txt";
Here is how it works:
1. When testing a property named N, LectroTest will check for a play-back file. If the file exists, LectroTest will search it for test
cases associated with N. If any such test cases exist, LectroTest will play them back before and in addition to performing the usual,
random testing of the property.
2. When performing the usual, random testing of a property named N, if a failure occurs (i.e., LectroTest finds a counterexample),
LectroTest will record the test case that caused the failure to the recording file, associating the test case with the name N.
NOTE: If you pass any of the recording or playback parameters to Test::LectroTest::Compat, you must have version 0.3500 or greater of
Test::LectroTest installed. (Module authors, update your modules' build dependencies accordingly.) The Test::LectroTest module itself,
however, has always ignored unfamiliar parameters, and thus these options are backward compatible with older versions.
SEE ALSO
Test::LectroTest gives a quick overview of automatic, specification-based testing with LectroTest. This module accepts failure recording
and play-back options.
Test::LectroTest::Compat lets you mix LectroTest with the popular family of Test::Builder-based modules such as Test::Simple and
Test::More. This module accepts failure recording and play-back options.
LECTROTEST HOME
The LectroTest home is http://community.moertel.com/LectroTest. There you will find more documentation, presentations, mailing-list
archives, a wiki, and other helpful LectroTest-related resources. It's also the best place to ask questions.
AUTHOR
Tom Moertel (tom@moertel.com)
COPYRIGHT and LICENSE
Copyright (c) 2004-06 by Thomas G Moertel. All rights reserved.
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
perl v5.12.3 2007-08-30 Test::LectroTest::RegressionTesting(3pm)