Installing DB2 on Linux

A few links I found useful while installing DB2 on Debian/Gentoo, etc:

Understanding Memory Usage On Linux

Have you ever wondered why a simple text editor on Linux can use dozens of megabytes of memory? A recent blog posting explains how the output of the ps tool is misleading and how you can get a better idea of how much memory a process really uses.

How do I crash Linux?

Benefits of Linux

Linux can give you:

1. A modern, very stable, multi-user, multitasking environment on your inexpensive PC hardware.

2. Standard platform. Linux is VERY standard–it is essentially a POSIX compliant UNIX.

3.Unsurpassed computing power, portability, flexibility, and customizibility.

4. Advanced graphical user interface.

5. Dozens of excellent, free, general-interest desktop applications.

6. Thousands of free applets, tools, and smaller programs. “Small is beautiful” goes well with Linux philosophy.

7. Hundreds of specialized applications built by researchers around the world.

8. Support for commercial programs including all the big databases (Not Windowz).

9. A truly great learning platform.

10. Excellent networking capability.

11.Connectivity to Microsoft, Novel, and Apple networks. Reading/writing to your DOS/MS Windows and other disk formats.

12. Programming languages and tools for development.

13. Freedom from viruses, “backdoors”

14. Linux is not owned

And many many more …

Recovering damaged Superblock

Making ISO image from CD

Installing packages using ports in FreeBSD

Suppose you want to install package lsof

# cd /usr/ports/sysutils/lsof 

Once inside the lsof directory, you need to compile, or “build”, the port. This is done by simply typing make at the prompt. Once you have done so, you should see something like this:

# make
[extraction output snipped]
>> Checksum OK for lsof_4.57D.freebsd.tar.gz.
===> Patching for lsof-4.57
===> Applying FreeBSD patches for lsof-4.57
===> Configuring for lsof-4.57
[configure output snipped]
===> Building for lsof-4.57
[compilation output snipped]

The next step is to install the port. In order to install it, you simply fire the make command

# make install
===> Installing for lsof-4.57
[installation output snipped]
===> Generating temporary packing list
===> Compressing manual pages for lsof-4.57
===> Registering installation for lsof-4.57
This port has installed the following binaries
which execute with increased privileges.

You are done :)

How to install RPM packages using RPM

1. Install package
rpm -ivh foo.rpm

2. Upgrade package
rpm -Uvh foo.rpm

3. Erase package
rpm -e foo

4. Package information
rpm -ql foo.rpm –> Display list of files in package
rpm -qd foo.rpm –> Display list of documentation files
rpm -qc foo.rpm –> Display list of configuration files

Sync Samba and Unix password

Active FTP vs. Passive FTP

Active FTP

In active mode FTP the client connects from a random unprivileged port (N > 1024) to the FTP server’s command port, port 21. Then, the client starts listening to port N+1 and sends the FTP command PORT N+1 to the FTP server. The server will then connect back to the client’s specified data port from its local data port, which is port 20.

When drawn out, the connection appears as follows:

Passive FTP

In passive mode FTP the client initiates both connections to the server, solving the problem of firewalls filtering the incoming data port connection to the client from the server. When opening an FTP connection, the client opens two random unprivileged ports locally (N > 1024 and N+1). The first port contacts the server on port 21, but instead of then issuing a PORTPASV command. The result of this is that the server then opens a random unprivileged port (P > 1024) and sends the PORT P command back to the client. The client then initiates the connection from port N+1 to port P on the server to transfer data.

When drawn, a passive mode FTP connection looks like this:


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