I recently updated to the newest version, 9.10 AKA Karmic Koala and I love it. It’s fast and everything works perfectly. Or nearly everything…

The one thing that really annoyed me in this version was the MySQL terminal. All of a sudden after the upgrade ctrl+r for reverse search didn’t work anymore. And there was more…delete didn’t work either and esc+backspace was behaving weirdly too. Unfortunately I did not have time to look for a solution because of my work load. But then xmas came and here I am, stuck at home with the family, giving me a lot of time to research about those things that were very low on my priorities list. And I found a solution!

It seems that Ubuntu replaced libreadline with libedit. And readline is the library that provides all those cool command line capabilities. So let’s enable it again, but instead of compiling the whole thing again, let’s just use a wrapper, the readline wrapper!

First, let’s install it:

sudo apt-get install rlwrap

That’s it! Now all we need to do is to start mysql command line interface through rlwrap:

rlwrap -a mysql -uUSER -pPASSWORD DBNAME

To make things easier, let’s create an alias in our bashrc file.

vi ~/.bashrc

And add the alias:

alias mysql='rlwrap -a mysql'

Credit: http://ubuntuforums.org/showthread.php?t=1147183

As opposed to rsync, unison is a two way file synchronizer. Similar to MySQL’s master to master replication. To set it up in Ubuntu (Intrepid) keep on reading…

1. Install unison on both servers

apt-get install unison

2. Create a script to add to crontab to call unison periodically

unison -numericids -owner -silent -times -contactquietly -batch -auto -log -logfile /var/log/unison.log profile_file 2>&1

3. Create the above mentioned profile file on ~/.unison/profile_file.prf

root = ssh://server_ip//path/to/root/dir
root = /path/to/root/dir
ignore = Regex .*(cache|Cache|te?mp|logs?).* # ignore log and cache files

That’s it! Now add the following line to your crontab to execute it every 5min

*/5 * * * * /path/to/my_unison_script.sh

After a few days of running this I found that sometimes one unison execution would overlap another. To resolve this I found a little tool called lockrun

To get it to work I did:

1. Download the source code from the official lockrun website

wget http://unixwiz.net/tools/lockrun.c

2. Build/install as shown in http://unixwiz.net/tools/lockrun.html

gcc lockrun.c -o lockrun
sudo cp lockrun /usr/local/bin/

3. Change the previous crontab line to use lockrun

*/5 * * * * /usr/local/bin/lockrun --lockfile=/tmp/hosting.lockrun -- /path/to/my_unison_script.sh

All done!!!