Unknown column 'plugin' in 'mysql.user'

When migrating from MySQL 5.1 to version 5.6, when creating a user, an error occurs:
ERROR 1054 (42S22): Unknown column 'plugin' in 'mysql.user'

How to fix:

use mysql;
ALTER TABLE `user` ADD `Create_tablespace_priv` ENUM('N','Y') NOT NULL DEFAULT 'N' AFTER `Trigger_priv`;
ALTER TABLE `user` ADD `plugin` CHAR(64) NULL AFTER `max_user_connections`;
ALTER TABLE `user` ADD `authentication_string` TEXT NULL DEFAULT NULL AFTER `plugin`;
ALTER TABLE `user` ADD `password_expired` ENUM('N','Y') NOT NULL DEFAULT 'N' AFTER `authentication_string`;

HowTo: Resize ext3 partitions without data lose.

Howto forge released a good tutorial on resizing your ext3 partitions without loosing any data on it. It covers shrinking,enlarging and merging of ext3 partitions. If you don’t don’t use LVM then this tutorial would be good for you.
Access the tutorial here.
Howto forge homepage.

Setting the root password on MySQL

I just installed MySQL version 4.1.20 on my CentOS 4.4 server. The default install of MySQL server uses a blank password for root so I had to have it changed. I also set the MySQL service to start up every time my machine boots up.
This is how I did it;
Method 1
1. # yum -y install mysql-server (This will install the mysql binaries)
2. # chkconfig mysqld on (Adds mysqld to the startup services)
3. # service mysqld start (Starts the MySQL server)
4. # mysql -u root@localhost (Brings up the MySQL console)
5. #mysql> set password for root=password(‘password’); (Sets the root password to “password”)
6. #mysql> reload privileges; (Reloads the grant tables)
Method 2
1. # mysql -u root (Brings up the MySQL console)
2. #mysql> use mysql (Use the mysql database)
3. #mysql> update user
-> set password=password(“password”) (Sets the root password to “password”)
-> where user=”root”;
4. # reload privileges; (Reloads the grant tables)
That’s it, the next time you want to get the MySQL console up you’ll have to run #mysql -u root -p to get the password prompt.
Post-Installation Setup and Testing at MySQL
Update:
This will work too.
/usr/bin/mysqladmin -u root password ‘new-password’
/usr/bin/mysqladmin -u root -h pandora.crib password ‘new-password’

.htaccess password generator

Use this tool at Dynamic Drive to automatically generate all the code needed to protect a directory on your site. Below are the 2 files generated by the tool. .htaccess goes into the folder that you want to protect and .htpasswd should be in a folder not accessible from the web. I normally put my .htpasswd file in my apache’s base folder.
.htaccess file
AuthName "Restricted Area"
AuthType Basic
AuthUserFile /home/mydir/.htpasswd
AuthGroupFile /dev/null
require valid-user
.htpasswd file
danny:8UAaVrlw.58f6
Get the tool here.

Screen | Linux Command

When you run commands and programs in a command prompt on Linux, the programs or commands only run while the command prompt session is open but as soon as the command prompt session is terminated for whatever reason, the commands or programs running within the command prompt session will also get terminated.
I use wget to download files from the internet using my putty console all the time. Imagine downloading a 500mb file and then suddenly putty crashes causing my session to terminate along with it. There goes my 500mb file download!! I so wished I had known about the “Screen” program then.
The screen program is a magnificent utility. Screen basically starts a session within the the session that you logged in with. So, if your putty session suddenly crashed don’t worry, the screen session would still be running in the background. Log in again to the server using putty and you should be able to retrieve the screen session you initiated earlier.
# screen
This starts a screen session.
# Ctrl + A followed by D
This will detach your screen session and return you to the original session you logged in with. Your screen session will now be running in the background.
# screen -r
This command will resume your previous screen session.
# Ctrl + A followed by Ctrl + (back slash)
# exit
You could run either command above to end a screen session.
# Ctrl + A followed by “
This command will list all the available screen sessions running if there are.
Usefull Links:
O’REILLY Linux Command Directory
Inside Open Source

-bash: /usr/bin/crontab: Permission denied

” -bash: /usr/bin/crontab: Permission denied “.
I was getting this error earlier today while trying to add cron jobs for my login on my SLES 10 box at work. Turns out that all users in SLES 10 by default have no access to cron.
The fix is to add the user to the “trusted” group in the group file (/etc/group). Let’s assume mu login is “elf”.
1. Make sure you are “root”.
2. #usermod -G trusted elf
This will add the user to the “trusted” group.
3. #id elf
Display groups the user belongs to. Make sure “trusted” is on the list too.
The output might look like this. “uid=502(danny) gid=502(users) groups=502(elf),11(trusted)”
4. #su – elf
Change user
5. #crontab -e
Add/Remove/Edit user cron jobs.
6. #crontab -l
List user scheduled cron jobs
Please do comment if you have an alternative way to accomplish this or if I made a mistake.

Bash and command line keyboard shortcuts

Shortcut keys for the bash and commad line interface.
Ctrl + A – Moves cursor to begining of line.
Ctrl + E – Moves cursor to end fo line.
Ctrl + K – Clears command line from cursor position till end of line.
Ctrl + U – Clears command line from cursor position till begining of line.
Ctrl + W – Clears first word to the left from cursor position.
Ctrl + Y – Paste any value previously deleted by Ctrl+K,Ctrl+U and Ctrl+W.
Tab Key – Auto compelte a partial typed command.
Ctrl + R – Followed by characters with search through the recent command history.
Crtl + D – Quits bash if used in a blank command line.
Ctrl + L – Screen refresh.
Ctrl + C – Kills current process.
Ctrl + Z – Suspend a process. Use command “bg” to execute the process in the background and “fg” to bring the process back to the foreground. The command “jobs” will list the available processes you can manipulate.
That’s it. Hope the commands help you. If i missed out anything please do comment.