Why is Weekend so important to programmer?

Weekend is a time for programmer to do his things on his own way. 


Those two days are filled with exploration, excitement and doing things beyond what he always do on weekdays. Those are the days where he enhances his programming practice which is his codebase. Those are days where he is learning new things and formulating a simple application to showcase it. Those are days of the week that he is so true, that no one may disturb him while he is on his logical and imaginative mind.


On those days, he will do things on his way, we will make sure that every minute counts. He will read everything that catches his mind and will implement it. He will do diffucult bugs also sometimes enhance it on that day. And as that weekend close, he will never see any TO DO on his codebase.


Those days, he will go beyond his capabilities, he will push himself to create and learn new things for only forty-eight hours. Sometimes he will fail on doing it but still he is happy, because he learn again new technology and created something that has put him to what makes him original on his programming life.


On those days, he will be staying on his cave, maybe it will be a room, in the living room or maybe even in the kitchen. After forty- eight hours of meditating, he will evolve as a new man. He now has a new skill set on his sleeve, new methodology that he discovers more efficient, a new thinking that had been formulated on the two days of rumination and that novel view that programmer is never selfish, for he will be grateful to share it to the world. He knows that what he discovered on that two divine days will be of great use and not just meant on a recycle bin. Most of all, he know that if he share it to others, what he had discover on that two days will unlock more astounding designs that programmers can use.


Those are the days when the programmer rest. It‘s just that REST for programmer is doing things beyond their limits and a means to breakaway.  Rest for him is learning new things, creating and producing something valuable through them.

Add new YUM repository Fedora

All the RPM (RedHat Package Manager) that are based linux (such as Fedora, CentOS, RHEL) use yum for software management. Yum always help you to install application through remote repository of rpms.

Yum Repository in Deeper Sense

If you want to tween yum, you can do so by editing /etc/yum.conf (I will explain the configuration next week). And by default, all the configuration of yum repository are located on /etc/yum.d and /etc/yum/repos.d dir. (defined by reposdir)

Installing RPM direct from the repo

If you know the location of an RPM on the web, you can install it by adding it’s remote repository (so RPM does not belong to any repository) just by:

        rpm -Uhv protocol://location-of-file-in-the-web

where U means upgrade; this will install the new version (if your rpm is the new version) and remove the old one.

v means verbose; this will print verbose information - error messages or warning

h means hash; this will print 50 hash marks as the package archive is unpacked.

protocol://location-of-file-in-the-web - this represent the location of your rpm to be installed on your local computer.

        rpm -Uhv http://origin-download.mono-project.com/download-stable/openSUSE_11.4/x86_64/glib-sharp2-2.12.10-27.11.x86_64.rpm

 

Installing 3rd party repository manually

Based on the example, Let’s say I wanted to add a repository where glibsharp2 is located. So first I will create a file on /etc/yum.repos.d named mono.repo (to make it more meaningful)

        cd /etc/yum.repos.d

        vi mon.repo

Then put:

        [mono]

name=mono

baseurl=http://origin-download.mono-project.com/download-stable/openSUSE_11.4/
enabled=1
gpgcheck=1
gpgkey=http://origin-download.mono-project.com/download-stable/openSUSE_11.4/repodata/repomd.xml.key

save and close it by pressing escape and :wq and enter.

where

[mono] - repository name

name=mono - repository name in more human readable string

baseurl=http://origin-download.mono-project.com/download-stable/openSUSE_11.4/ - the url of the repository, this location must include the content which is the repodata directory. This repodata contains all the information of the repo.

enabled=1 - means this repo is enabled, 0 if disabled.

gpgcheck=1 - security feature is enabled, 0 if disabled. This uses GPG key.

gpgkey=http://origin-download.mono-project.com/download-stable/openSUSE_11.4/repodata/repomd.xml.key - location of the gpg key of the repo

Sometimes you have to manually import the gpg key of the repository which is done by:

rpm --import http://origin-download.mono-project.com/download-stable/openSUSE_11.4/repodata/repomd.xml.key

If you need more information about rpm, yum and it’s configuration just:

man yum.conf

man yum

man rpm

Hope this can help you.. :)

Branching and Merging for Git

Branching is a technique wherein you can create an active line of development for your source code. Through this, you will be able to create a separate copy of your source code  that you can edit and merge to your original or other copies (branches).

In order to create a branch named “testing” on an existing git repository:

git branch testing

This will create a branch named testing.

In order to check your local branch:

        git branch -l

To check for your remote branch

        git branch -r

To check all available branch for your repo:

        git branch -a

Example you inputted git branch -l, this will list all the branch on your local repo

        testing

        *master

The asterisk marks the branch you are currently on. For you to transfer to testing just:

        git checkout testing

For you to transfer to master again, commit your changes first for testing branch then checkout master:

        git checkout master

Therefore, the change you made on the testing branch is not visible on master.You can change then commit it.

If you are on master and you want to merge the changes of master and testing, you can do so by running:

        git merge testing

If you’re on testing:

        git merge master

Sometimes, there are conflicts on merging the two branch (conflict means you edit the same file on the same line). You can see all the file that has conflict by the use of:

        git diff

If you can’t fixed the conflict on files and decided to give up you can:

        git reset --hard HEAD

or if the change is committed use:

        git reset --hard ORIG_HEAD

If you want to delete testing branch, just execute:

        git branch -d testing

REFENCE:

http://book.git-scm.com/7_glossary.html

http://book.git-scm.com/3_basic_branching_and_merging.html

The Promise

I promise to myself that will be active on updating this blog. Come to think of this, I learn new things everyday which means that I must have one post per day in this blog, may it be simple or chart topping, I must journal it and post it in here. :)

Changing user password

When you install mysql using yum on a rpm based machine, it's default root password is empty. To change it you can use mysqladmin command. The command is like this:

mysqladmin -u root password NEWPASSWORD

if you want to change a root with a existing password, you can use this:

mysqladmin -u root -p 'oldpassword' password NEWPASSWORD

Changing MySQL password for non-root user


To change a normal user password you can use the same syntax as changing root with existing password:

mysqladmin -u username -p 'oldpassword' password NEWPASSWORD

Chaning User Password using MySQL command


You can also used the MySQL command line to update user's password, MySQL stores username and passwords in a table inside MySQL database.

1. Login to mysql server.
2. Use mysql database.
3. change password for username by entering:  update user set password = PASSWORD("NEWPASSWORD") where user='username';
4. Lastly, restore the privileges: flush privileges;

Extracting tar.bz and tar.bz2 on Linux

To extract a tar.bz2 file, use this command:

tar -jxvf filename.tar.bz2

where j means  it's for bzip2, xz, lzip and lzma compress extension.

To extract a tar.gz file, the command is:

tar -zxvf filename.tar.gz

where z means it's for gzip, gunzip and ungzip compression extension
x is extract files from filename.tar.gz
v is to list all the file proccessed
f is to extract filename.tar.gz

if you want to specify the directory to where the extracted file go, use this command:

tar -xvzf file.tar.gz -C directory

where C means  put extracted file to directory

How to know MySQL activities: MysqlBinLog

Mysql has this new (maybe it's old) logging system called binary log (also called logbin). This consists of files containing events that describe  modifications to database contents. This file is saved in binary format by the server and the only way to read this binary file in human form is through mysqlbinlog utility. (By the way, this binary log is used by slave to replicated master's schema, so this is really a power file).

To execute mysqlbinlog in your terminal:

mysqbinlog [options] logfile

like:

mysqlbinlog /var/lib/mysql/localhost-bin.000005 

This command will then display the content of the binary file localhost-bin.000005. The content of this file is:

# at 430

#111110 21:55:34 server id 1  end_log_pos 537 Query thread_id=2 exec_time=0 error_code=0

SET TIMESTAMP=1320933334/*!*/;

update Company set name='hello' where id = 1

This 1st line which is "# at 430" means that the starting position of the event in the binary log file is 430. On the second line, the number's with colon is the timestamp of the event (this is when the event happen). The "server id 1" state that the event happen on server id number 1. "end_log_pos 537" indicates that the next event starts at 537. "thread_id=2" says that the thread that execute the event is id 2. "exec_time=0" means the time spent to execute the event. Lastly, the last line is the event executed by the server. As you can is it is an update.

For your server to log event as a binary file, you must first enable it. To enable, you must edit the my.cnf and append log-bin=path.

The normal formal of binary file logs is host_name-bin.###### and store in /var/bin/mysql directory.

Mysqbinlog I commonly use:

mysqbinlog /var/lib/mysql/localhost-bin.000005 > ~/mysql5.sql

This will put all the content of the logbin to the file mysql5.sql.

mysqbinlog --start-datetime="2011-11-11 11:11:11"  /var/lib/mysql/localhost-bin.000005

This will only display event that is log on and after 2011-11-11 11:11:11.

mysqbinlog --stop-datetime="2011-11-12 11:11:11" /var/lib/mysql/localhost-bin.000005

This will only display event that is log before 2011-11-12 11:11:11.

mysqbinlog --database=liims2 /var/lib/mysql/localhost-bin.000005

This will only display event that is invoke on database liims2.

Hope this will help you on using mysqlbinlog utility.

Reference:

http://dev.mysql.com/doc/refman/5.0/en/mysqlbinlog.html

http://dev.mysql.com/doc/refman/5.0/en/log-file-maintenance.html 

Updating from Fedora 15 to Fedora 16

I have update my fedora 15 to 16 successfully today. So know I will share you the step.

First install the new Fedora 16 gpg key.

rpm --import https://fedoraproject.org/static/A82BA4B7.txt

then upgrade all packages using this commands.

yum update yum

yum clean all

yum --releasever=16 --disableplugin=presto distro-sync

you must have a root permission to do all the command above. so use sudo or log in as a root

Maven - Installing Dependencies in your Local Computer

This is not something new to me. I just need to document this activity before I forget it again.

There are times when your .jar or api's are not in a central repositories for some reason. This is the time when installing dependencies in your local computer is applicable.

Here are the ways:

1. Install the dependency locally using the install plugin.

maven install:install-file -Dfile=foobar.jar -DgroupId=foo.bar -DartifactId=for-bar -Dversion=1 -Dpackaging=jar

2. Create your own repository and deploy it there. This is a fovrite method for companies with an intranet and need to be able to keep everyone in synch. There is a Maven goal called deploy:deploy-file which is simlar to the install:install-file goal.

On the two ways stated above, I normally used the 1st one if the project is been done by I alone. And if it is a team project, the 2nd ways is what I used.

Mysql Database Back/Restore

I have spent somethings research about this topic Back/Restore in Mysql and I found out that there are lot of ways to do this procedure but I choose this two:

• Mysqldump - this will create a dumpfile (also called textfile) or it will display the dump file on your console.
• Syntax: mysqldump -uMysqlUserl -p databaseName <>> filePath>
• mysql -uroot -p liims2
• after press enter will ask for password, display dumpfile of liims2 database as a whole in the console
• mysql --complete-insert -uroot -pmysql liims2 pnpa 
• display the dumpfile on console of pnpa table with complete insert query
• mysql -uroot -pmysql liim2 >> /opt/mysql_backup.sql
• backup all the data in liim2 database and put it on /opt/mysql_back.sql file
• Mysql restore function - will restore you data from a dump file or text to a specific database
• Syntax: mysql -uMysqlUserl -p DatabaseName << Backup.sql
• mysql -uroot -pmysql liims2 << /opt/mysql_backup.sql
• restore all that data defined on /opt/mysql_backup.sql to liims2 database