Motivation

And now please ask me:
"Rocco, why did you planned to implement another shell?"

The pksh exists because I am a network programmer, an enough curiuos programmer, and I want to learn more of network protocols. I usually write at work applications over TCP/IP since more than 15 years, and I often need to take a look at packets on the network for my daily job, while decoding some strange PDU or trying to understand an unexpected behaviour of my latest version of the software.

So, to learn more of protocols, and network programming in general, there is no way other than capturing and decoding packets on live networks. But I need a powerful network tool, not the usuals currently available on modern Unix distributions. GUIs and web pages are nice, but tcpdump and trafshow are still good friends even if they are awkward in some respects and pretty useless for directed LAN investigation.

Unfortunately none of the existent network tools are programmable enough to take a deep look at my LAN segment using only with few lines of code or just hitting few keystrokes on my keyboard.

Moreover I also am a pipe (|) fanatic, and, in the spirit of Unix, I usually want to filter the output and pass it to subprograms.

None of the network tools of the net have the pipe command available. So, instead to reinvent the wheel, I just started to think to reuse the pipe mechanism that all the Unix shells have already implemented.

I was so excited to issue commands like:
pksh> pkhost | head -25 | mail -s "top 25 hosts as `date'" rocco@ntop.org
to send at my email address the top 25 hosts in terms of total bytes sent/received at a given date.

I started to think that I needed a ntop version at fingers power, a ntop CLI version. And more specific I realized that I needed to embed ntop functionalities into a shell. The ntop web-based daemon offers several pages with so much information that cannot be reproduced on the terminal, or at least they may be reproduced but need to be splitted in several outputs, and then driven by several specific commands.

So I started thinking to an extension of the shell and pksh was born as an extension of the tcsh, which is my preferred login shell.

The tcsh was the choice for the shell! I do not know if it is the best shell available on the Internet. But it is my daily shell since my first login on a Unix system (Digital Ultrix), so the tcsh was the choice by default.

And started to do my best to name and implement pksh commands, as particular views of the ntop html pages.

Programming inside the shell is an exciting activity and day by day a lot of functionalities are discovered and ideas become reality, so I also tried to go ahead with shell-specific features, for example adding variables on the fly to the shell for globbing and hosts completions.

I said to Luca Deri, the ntop's author, that it is impossible with html :-)

But I am sure I am so far to include all what really a networker needs, and therefore I need the feedback of the Internet community to understand the need for such tool in order to continue my effort and add support for more network data-link interfaces, more protocols, more built-ins, more data rendering, more of other.