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Welcome to My Blog

This is to share my IT experience with friends all around the world.
I have been working in Linux Fedora Systems for more than 8 years. Its fun to share knowledge and learn..
As everyone knows when a problem arises in your systems "googling" is the way that many depend on..

All the posts here are my working experiences during my working life.. So you can count on it..

I have added the references where I got help in solving IT issues


Thursday, October 9, 2014

Limiting a User to Read few columns on a table in MySQL Database

I wanted to limit a mysql user to read only few fields of a table in a MySQL database. I used select grant privileges command to get the desired output.

For example if a user 'test_user' is requested to access field1, field3 and field6 on the test_table in test_db at 192.168.1.1 server following user creation will work.

The user has to be added at the mysql server running on 192.168.1.1. I have assumed the user test_user is connecting from 192.168.1.2

mysql> GRANT SELECT (`field1` ,`field3`, `field6`)  ON `test_db`.`test_table` TO 'test_user'@'192.168.1.2' identified by 'test_pw';


If you want to allow the user to modify the data in the table you may use 'UPDATE' privilege instead of 'SELECT' privilege.

References

Tuesday, September 23, 2014

How to monitor user login history on CentOS with utmpdump

A very useful reading for CentOS admins http://xmodulo.com/2014/09/monitor-user-login-history-centos-utmpdump.html.

I was using `last` and `lastb` earlier but feels we can get more information with `utmpdump`. Thanks for Gabriel Cánepa for his article.

Some short notes from his article

utmpdump /var/run/utmp  - show who is currently logged on and what they are doing, and also by uptime to display system up time

utmpdump /var/log/wtmpshow the listing of last logged-in users

utmpdump /var/log/btmp  - show the listing of last failed login attempts

These files are used in last and `lastb` commands to show details of login but by using utmpdump we get more flexibility for filtering

Upgrade PHP 5.3.3 to 5.4 in CentOS

Sometimes we need to upgrade PHP version inbuilt with the OS to newer version. We have been using CentOS for sometimes. It was requested to upgrade PHP to php5.4 in CentOS 6.5 and I have followed the below given link. We were able to upgrade PHP 5.3.3 to  PHP 5.4.32 (cli) (built: Aug 22 2014 07:07:38) smoothly.

If you have such requirement it is safe to follow the link http://www.shayanderson.com/linux/centos-5-or-centos-6-upgrade-php-to-php-54-or-php-55.htm

Even though it is bit old still works fine :-)