Good reference on Crontab

Got rusty on this good old utility crontab and found a very good article of crontab. Read Crontab – Quick Reference

SGI® Altix® UV Scales Microsoft® Windows Server® to Its Maximum

Interesting hardware achievement for SGI Altix UV which is able to scale Four Times the Scale of HP, 2.6 Times the Scale of IBM.

From the website, SGI® Altix® UV Scales Microsoft® Windows Server® to Its Maximum, this table summarise SGI Altix UV achievement......

Vendor	Platform	Architecture	Physical Cores
SGI	UV 1000	Intel x86	256
IBM*	X3950 M2	Intel x86	96
HP**	Proliant DL980 G7	Intel x86	64

Red Hat Summit 2010 Presentations slides

A good respository of latest technologies presentation slides that was presented at Boston 2010. See Red Hat Summit Presentations

Understanding the difference between .bash_profile, .bash_logout and .bashrc

Important Notes on bash file

1. These files in your home directories have special meaning to bash, providing a way to setup the account environment when you log in and when you invoke another bash command
2. If the files are not found in your home directory, you are using the default system on /etc/profile
3. Most important is the .bash_profile which is read and the command in it is executed by bash every time you logged on to the system.
4. .bashrc is invoked when you start a new shell or by typing bash on the command line.
5. If you just need to have the same command run regardless of  a subshell or a login shell, you can easily source .bashrc and hence execute .bashrc from within .bash_profile
6. .bash_logout is read and executed every time a login shell exits.

Locking and Unlocking user account on Linux

If you need to politely refuse a login for a user, you use the command

# usermod -s /sbin/nologin UserLoginName

To unlock the user account

# usermod -s /bin/bash UserLoginName

Alternatively, you can use the commands to lock the user account

# passwd -l UserLoginName

To unlock the user account

# passwd -u UserLoginName