Linux has all the tools you need to generate a random password. This can be accomplished by a special file /dev/random, that serves as a random number generator.

If you are planning to discard your old hard disk, make sure that they do not contain any valuable information when they head out of your door. The last thing on your mind is the potential of having your identity stolen from sensitive information stored in that hard disk.

To perform disk usage monitoring of users on a UNIX system, you will, first of all, need to determine the home directories of the users. You might ask, “Aren’t all the user home directories found under /home?”. Well, typically yes, but it’s not always true.

Netcat is often known as the swiff army knife for TCP/IP. It’s features include but not limited to UDP/TCP port scanning, file transfers, tunneling of UDP over TCP, port forwarding and so on.

I have a dual-boot computer that boots Ubuntu and Windows 7. Whenever I boot into Ubuntu, the BIOS clock is automatically set to UTC time, even though my current timezone is UTC+8.

A couple of readers, upon reading this article to calculate yesterday’s date in a shell script, have requested for a similar script that can be used to calculate tomorrow’s date.

In modern UNIX and Linux systems, user passwords are encrypted and stored in the /etc/shadow file. On BSD systems, the passwords are kept in the /etc/master.passwd file. The encrypted password field in the file contains more than just the encrypted password, it contains additional information.

Linux is a very customisable UNIX like operating system. To date, there are more than a couple of dozen Linux distributions available, based on this Wikipedia list.

There are times when you will need to calculate yesterday’s date in a UNIX shell script to run some date sensitive cron jobs. There are currently no standard command line tools in UNIX to perform such date arithmetic.

If your organisation has password aging policy set for your UNIX servers, there is a possibility that the root account may also get locked out due to the existence of an expiry date set in the /etc/shadow file. Once the root account is locked, all jobs (cron, etc) that require root privileges may start to fail. To unlock the root account on a SUN SPARC machine, you will need to: