Posts Tagged ‘nickname’

The creator of C and UNIX Dennis Ritchie passed away R.I.P. Dennis

Thursday, October 13th, 2011

Dennis Ritchie old young picture

I just read the lwn.net – Linux Weekly news ‘s website the very sad news that one of the greatest modern day computer heroes Dennis MacAlistair Ritchie after a long illness has passed away in his home.

The original notification for this grieving news are on Rob Pike’s Google Plus wall , this is the original message:

Rob Pike - 1:02 AM - Public
I just heard that, after a long illness, Dennis Ritchie (dmr) died at home this weekend. I have no more information.
I trust there are people here who will appreciate the reach of his contributions and mourn his passing appropriately.
He was a quiet and mostly private man, but he was also my friend, colleague, and collaborator, and the world has lost a truly great mind.

For all those who haven’t heard about Dennis Ritchie , he was a computer scientist who developed the C Programming language and had an immeasurable influence on all kind of Modern programming.

C Programming Language cover Dennis Ritchie

Dennis worked on the development of Unix’s predecessor Multics as well as with Ken Thompson worked together in Bell Labs and are practically the fathers of UNIX.
Unix the Seventh Edition source code has later become the basis for the early UNIX BSD distributions. Among the most important technical contributions Dennis has done is the introduction of a Streams mechanism – pipes – (as called today in GNU/Linux and BSD and other unices).
Ritchie’s C Language creation on top of Ken Thompson’s B Programming language has been standartized and become the de-facto standard for almost every modern existing OS around.
Moreover dmr has been among the co-creators of Plan 9 Operating system (which is currently open-source distributed) as well as coded a few bits for the Inferno OS which today is known under the code name Vita Nuova

Unix Live Free or die Bell labs early UNIX logo

dmr (the hacker nickname of Dennis) lines up across the most notable computer hackers of all times. He received U.S. national Medal of Technology in 1999 from president Bill Clinton for his contributions to co-inventing the UNIX operating system and the creation of C Language

Denis Ritchie receives national prize in 1999 for Technology from president Bill Clinton
To sum it up DMR is just an “icon” in the computer geek world and his memory will surely live forever in the hacker undeground and computer geek culture.

Dennis Ritche near a personal computer picture

A few quotes dmr is so famous with:

"I am not now, nor have I ever been, a member of the demigodic party."
"Usenet is a strange place."
"UNIX is very simple, it just needs a genius to understand its simplicity."
"C is quirky, flawed, and an enormous success."
"We really didn't buy it thinking we'd have this enormous investment."

Here is also a short video telling a few words of UNIX history and showing Dennis Ritchie in his UNIX development years:

Farewell Denis! See you in Hacker’s paradise 😉

How to add cron jobs from command line or bash scripts / Add crontab jobs in a script

Saturday, July 9th, 2011

I’m currently writting a script which is supposed to be adding new crontab jobs and do a bunch of other mambo jambo.

By so far I’ve been aware of only one way to add a cronjob non-interactively like so:

                 linux:~# echo '*/5 * * * * /root/myscript.sh' | crontab -

Though using the | crontab – would work it has one major pitfall, I did completely forgot | crontab – OVERWRITES CURRENT CRONTAB! with the crontab passed by with the echo command.
One must be extremely careful if he decides to use the above example as you might loose your crontab definitions permanently!

Thanksfully it seems there is another way to add crontabs non interactively via a script, as I couldn’t find any good blog which explained something different from the classical example with pipe to crontab –, I dropped by in the good old irc.freenode.net to consult the bash gurus there 😉

So I entered irc and asked the question how can I add a crontab via bash shell script without overwritting my old existing crontab definitions less than a minute later one guy with a nickname geirha was kind enough to explain me how to get around the annoying overwridding.

The solution to the ovewrite was expected, first you use crontab to dump current crontab lines to a file and then you append the new cron job as a new record in the file and finally you ask the crontab program to read and insert the crontab definitions from the newly created files.
So here is the exact code one could run inside a script to include new crontab jobs, next to the already present ones:

linux:~# crontab -l > file; echo '*/5 * * * * /root/myscript.sh >/dev/null 2>&1' >> file; crontab file

The above definition as you could read would make the new record of */5 * * * * /root/myscript.sh >/dev/null be added next to the existing crontab scheduled jobs.

Now I’ll continue with my scripting, in the mean time I hope this will be of use to someone out there 😉