2013-09-06

Ich suhe einen Mann, der mich am 5.9 um 0:40 Uhr ...

A strange man is sitting at a S-bahn station. His note said, "Ich suche nach einem Mann, der mich am 5.9 um 0:40 Uhr auf dem Ku'damm tätlich angegriffen hat und dann weggelaufen ist. Er rief, dass er alle Ausländer, Chinesen und Japaner hasse. Wenn er wirklich dir Zukunft von Deutschland (und der Welt) retten will, dann kann ich ihm einen Job anbieten. Aber nur für kurze Zeit. Sehe sundayresearch.eu".

 My translation is "I am looking for a man who (physically) attacked me on Sept. 5th at 0:40 at Ku'damm and then ran away. He said, he hates all foreigner, Chinese, and Japanese. If he will really save the Germany (and the world), I can offer a job for him. But only the short time. See sundayresearch.eu."
A man with eyepatch.

His odd note.

2013-09-04

Passing command line options that have white spaces to a bash script: $* and $@

I always try to simplify a command line parser implementation regardless any programming language: C++, bash, ... To do that, I restrict the command line option to a regular form only. All my arguments should be

    '-arg_key value'

form. Even I want to specify a file name, my program needs an argument key, e.g., '-in_file input_filename. If you do in this way, each command line argument has the key, so I can put all the command line options to a map. This makes the command line parser simple. I usually don't need getopt library. Also I try to simplify the command line option support, means smaller number of command line options, and use a config file, which contains 'key = value' lines. This has two advantages: you can support negative values without confusing the command line option, easy to reproduce the test case.

However, this method still has a problem when the command line option includes white space. If I could, I will only try to use config files, but, in practice, it is not always the solution.

Let me show you such command line options. For instance, I want to pass a vector to my command as the following.

   command -eye_position '0 0 -10' -up_vector '0 1 0'
If I run a executable by hand from a shell, this is fine, but I usually want to run a command from a shell script like for automated tests. Here is an implementation example. test_1.sh:
  
-- test_1.sh --
echo "call with two args, but the second one has spaces."
echo "./test_2.sh args0 'args1_1 args1_2 args1_3'"
./test_2.sh args0 'args1_1 args1_2 args1_3'
-- test_1.sh --
The script test_2.sh just shows how the commend line options are passed.
-- test_2.sh --
echo "show the args with \$*."

for i in $*
do
    echo " $i"
done

echo "show the args with quoted \"\$*\"."

for i in "$*"
do
    echo " $i"
done

echo "show the args with \$@."

for i in $@
do
    echo " $i"
done

echo "show the args with quoted \"\$@\"."

for i in "$@"
do
    echo " $i"
done
-- test_2.sh --
What I want to get in the \verb|test_2.sh| is two arguments as the following:
  • $1: args0
  • $2: args1_1 args1_2 args1_3
Please note, in the second argument has while spaces. The execution result of the script is as following.
-- result --
call with two args, but the second one has spaces.
./test_2.sh args0 'args1_1 args1_2 args1_3'
show the args with $*.
 args0
 args1_1
 args1_2
 args1_3
show the args with quoted "$*".
 args0 args1_1 args1_2 args1_3
show the args with $@.
 args0
 args1_1
 args1_2
 args1_3
show the args with quoted "$@".
 args0
 args1_1 args1_2 args1_3
-- result --
If I use $* or $@ only, the white space separates the second argument, and made four arguments. To prevent this, I quote the arguments in the script,but "$*" becomes now only one argument. The "$@" is the one I wanted. This is the difference between $* and $@ of bash. This is a detail, and not necessary to know about it I Think. However, if you know it, you are a bit happier than before, I wish.

Myron Krueger's Amazing demo in 1988.

Myron Krueger's Amazing demo in 1988.

This video below is Myron Krueger's 1988's demo. It is one of the origin of virtual reality and the interactive art. It includes 'zoom in' gesture by two fingers and moving around a figure by hand or finger gesture. It is common in these days on a smart phone and a tablet. (see around 4:30).

http://youtu.be/dmmxVA5xhuo?t=4m30s

But I have a bit strange side story. last year (2012), Apple win Samsung in lawsuit and get 1 billion dollars. One of the Apple's inventions is this zoom in effect by fingers.

http://www.ndtv.com/article/world/samsung-apple-lawsuit-penalty-of-1-billion-dollar-slashed-in-half-337277

Apple invented this ``technology'' in 2005 as I read.

More strangely, someone invented this technology in 1993, and he won the lawsuit against Apple.
http://easthamptonstar.com/News/2013829/Springs%E2%80%99-Own-Beats-Apple

Myron Krueger's demo is magnificent in many ways. The demo itself is great. It also shows these lawsuit has no meaning, and also shows the case of the patent system isn't working.

2013-09-03

I just found that some reason, Google translate doesn't like number 8 and prefer 6.