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One-liner to copy remote MySQL database to local computer

Posted on July 23, 2011

The following commands dump a MySQL database from a remote server and create a corresponding database on the local computer.

The instructions have been tested on OSX and Linux (Ubuntu/Debian). On-line SSH compression is applied, so transferring SQL files, which are text content and compress well, should be around 6x faster than normal.

(Well… actually the script is six lines, but because this is my blog I’ll decide it doesn’t count)

The script

  • Remotely runs mysqldump and puts the result to a local file
  • Creates a MySQL database and corresponding user with full access to this database
  • Reads the content of mysqldump to the newly created database
 ssh user@dserver.com -C -o CompressionLevel=9 mysqldump -u YOURDATABASEUSER --password=YOURDATABASEPASSWORD --skip-lock-tables --add-drop-table YOURDATABASENAME > YOURDATABASENAME.sql
mysql -uroot -p
create database YOURDATABASENAME;
connect YOURDATABASENAME;
source YOURDATABASENAME.sql
GRANT ALL ON YOURDATABASENAME.* TO 'YOURDATABASEUSER'@'localhost' identified by 'YOURDATABASEPASSWORD';

Leave out create database and GRANT for the subsequent runs – all data on the local computer will be replaced.

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Testing mobile websites with Firefox Mobile for PC (Fennec desktop)

Posted on July 8, 2011

Firefox Mobile (Fennec) has also desktop builds. They are very useful for mobile web site testing as the browser is fast, has real keyboard and is only one mouse click away.

Here are instructions how to run Firefox Mobile on Ubuntu Linux (tested on 32-bit Ubuntu 10.10)

wget http://releases.mozilla.org/pub/mozilla.org/mobile/releases/latest/linux-i686/fennec-5.0.en-US.linux-i686.tar.bz2
tar -xjf fennec-5.0.en-US.linux-i686.tar.bz2
cd fennec
./fennec

.. and thats all you need. It works out of the box! 400x times faster than using Android emulator browser.

There are also OSX and Windows builds available.

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Run your Python application using PyPy – it’s fast!

Posted on March 26, 2011

Try your Python application with PyPy, the new hot Python JIT compiler

  • Your program will run faster…
  • … faster…
  • and ..faster!

Here are quick instructions for using PyPy on OSX. You should be able to apply these instructions to other UNIX systems as well.

Install PyPy by getting binary tarball.

wget http://pypy.org/download/pypy-1.4.1-osx64.tar.bz2
tar -xjf pypy-1.4.1-osx64.tar.bz

Install Distribute / easy_install command (setuptools fork) in order to install third party libraries.

cd pypy-1.4.1-osx64
wget http://python-distribute.org/distribute_setup.py
bin/pypy distribute_setup.py

Install libraries – easy_install seems to run just fine on PyPy as long as you don’t try to install Python native extensions

bin/easy_install plac # command line parser
bin/easy_install iso8601 # date format parser

Then run your application

~/code/pypy-1.4.1-osx64/bin/pypy exceptionanalysis.py     -s=2010-01-01T00:00:00 /Users/moo/xxx/log/client1.log

In my case the application was a simple log analyzer based on Python generators (code will be posted later). It reads a text file and tries to interpret it. The script utilizes only one CPU core and thus is very CPU bound. The speed comparison results are

  • With Python 2.4: Completed in 111.08 seconds
  • With PyPy: Completed in 30.39 seconds

That’s almost 4x speed-up!

Things did not work with PyPy

  • import multiprocessing – was not hard dependency, needed to comment out in plac_ext

Here is the traceback if anyone can help:

Traceback (most recent call last):
 File "app_main.py", line 53, in run_toplevel
 File "exceptionanalysis.py", line 20, in <module>
 import plac
 File "/Users/moo/code/pypy-1.4.1-osx64/site-packages/plac-0.8.0-py2.5.egg/plac.py", line 35, in <module>
 from plac_ext import Interpreter, import_main, ReadlineInput, stdout, runp, Monitor
 File "/Users/moo/code/pypy-1.4.1-osx64/site-packages/plac-0.8.0-py2.5.egg/plac_ext.py", line 7, in <module>
 import itertools, traceback, multiprocessing, signal, threading
 File "/Users/moo/code/pypy-1.4.1-osx64/site-packages/multiprocessing-2.6.2.1-py2.5-macosx-10.6-i386.egg/multiprocessing/__init__.py", line 87, in <module>
 import _multiprocessing
 File "/Users/moo/code/pypy-1.4.1-osx64/site-packages/multiprocessing-2.6.2.1-py2.5-macosx-10.6-i386.egg/multiprocessing/_multiprocessing.py", line 7, in <module>
 __bootstrap__()
 File "/Users/moo/code/pypy-1.4.1-osx64/site-packages/multiprocessing-2.6.2.1-py2.5-macosx-10.6-i386.egg/multiprocessing/_multiprocessing.py", line 6, in __bootstrap__
 imp.load_dynamic(__name__,__file__)
AttributeError: 'module' object has no attribute 'load_dynamic'

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Fixing a misbehaving terminal after after software interruption (pdb) or messed up output

Posted on March 23, 2011

Preface

Your terminal on Linux or OSX may end up to a bad state.

  • You cat a binary file to terminal
  • You interrupt pdb or some other application reading lines in a bad way

Symptoms

  • New lines don’t work
  • You cannot see your own typing to terminal
  • Backspace stops working

Fix

Type command

stty sane

This may fix some problems without needing to restart the terminal. More info.

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