Posts Tagged ‘text’

« Older Entries
Newer Entries »

How to convert SVG to PNG graphic formats (using GUI and console) on GNU / Linux and FreeBSD

Wednesday, December 7th, 2011

SVG to PNG Convert on GNU / Linux FreeBSD using command and GUI

I’ve playing trying to learn InkScape – The Open Source vector graphic editor .By so far I’m quite impressed on how easy this program is learned and how easy graphical manipulation with this nifty program can be done.
The default format in which InkScape saves its files is SVG (Scalable Vectors Graphics). For all those unfamiliar with SVG – SVG is an open (free format) format developed in 1999 which insetad of containing binary data like PNG or JPEG does contain plain XML content. SVG being consisted of plain XML has multiple advantageous, the most important one makes it easy for text and visual data to be displayed among different program svg readers in absolutely identical way. Besides that the format if read with plain text editor like vim or emacs can be altered directly via the source.
Being multi system interoperable makes SVG as a great format for text and visual data storage in HTML5, actually SVG is already a part of the HTML5 html coding standard. And most probably its adoption rate will raise up drastically as soon as HTML5 starts substitute HTML4 and lower web standards.

Anyways I’m slipping away from the aim of this post so I’ll stop blabbering on how great SVG is and let people check it out for themselves (if not already).

Going back to the aim of my article to show How to convert SVG to PNG graphical extension on GNU / Linux and FreeBSD

After producing a bunch of files with InkScape I realized the default format in which Inkscape stores its files is SVG , this was okay with me but since I wanted to have my experimental produced content in PNG I needed a way to convert SVG to
My first logical guess was that The Gimp will be able to handle the situation and after opening my SVG file with GIMP and used the gimp File -> Save As option and give the SVGfile an extension of PNG , Gimp succesfully converted the file to PNG.

However I wanted to dig further and check out what is the standard accepted way to convert SVG files using a plain command. This will possibly be handy to me if I had to do something online (let’s say a website) which will accept SVG and will require the SVG files to be converted and also stored in PNG or other Graphic file formats.

After checking online, I’ve found a post which pointed me to librsvg2 which contains RSVG – (Turn SVG files into raster images.)

librsvg is available as a package in most mainstream Linux distributions nowdays, Fedora, Debian etc., as well as contains a port inside the FreeBSD ports system. Since I’m using Debian on my notebook where I installed and tested the command line SVG to PNG convertion the way I did it is:

noah:/home/hipo/Desktop# apt-get --yes install librsvg2-bin
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following NEW packages will be installed:
librsvg2-bin
0 upgraded, 1 newly installed, 0 to remove and 16 not upgraded.
Need to get 72.5 kB of archives.
After this operation, 180 kB of additional disk space will be used.
Get:1 http://ftp.nl.debian.org/debian/ squeeze/main librsvg2-bin amd64 2.26.3-1 [72.5 kB]
Fetched 72.5 kB in 0s (184 kB/s)
Selecting previously deselected package librsvg2-bin.
(Reading database ... 376046 files and directories currently installed.)
Unpacking librsvg2-bin (from .../librsvg2-bin_2.26.3-1_amd64.deb) ...
Processing triggers for man-db ...
Setting up librsvg2-bin (2.26.3-1) ...

Afterwards the exact convertion of my Inscape SVG file drawing.svg to drawing.png using rsvg I’ve done like so:

hipo@noah:~/Desktop$ rsvg drawing.svg drawing.png

The convertion results for me was 100% uniqueness between the file converted and the output PNG. Some people might wonder why I didn’t used Inkscape’s Export to Bitmap function and then use convert command part of ImageMagick in order to convert the produced Inkscape bitmap to PNG.

 

One other thing worthy to mention is on  Debian,  librsvg2-bin contains 2 more executable besides rsvg. One is the rsvg-view command which allows one to view SVG files using command line or Graphic enviroment, the other one is rsvg-convert which supports again SVG convertion to PDF and to PNG

Before proceeding with the other described ways to convert SVG to PNG earlier in this article, I give a try to Inkscape’s Export to Bitmap embedded function but the produced bitmap did not resembled the original SVG file so I decided to completely abandon this method
Maybe there is some particular reason of the chaotic way I’ve tested Inkscape to place random images sometimes going out of the field of a paper etc. which influenced the improper generation of Bitmap using Inkscape, despite that it seems InkScape needs some more development until the bugs in Bitmap producing get fixed and it can be freely used to produce Bitmaps.

Maybe there is some particular reason for the failure of Inkscape to produce a good BMP file, like for example the chaotic way I’ve tested Inkscape to place random images sometimes going out of the field of a paper borders etc.This should have influenced the improper generation of Bitmap using Inkscape, anyhow it seems InkScape needs some more development until the bugs in Bitmap creation get fixed.

By the way if you’re wondering how to convert PNG to bitmap BMP after, once having converted SVG to PNG this is easily doable with convert command, like so:

hipo@noah:~/Desktop$ convert drawing.png drawing.bmp

Maybe in future releases it will be a good idea if InkScape developers integrate a convertion to other formats this will make it handy and make surely these nice program more popular among users. Hope this is helpful. Cheers and as RMS likes to say Happy Hacking 😉

Tags: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,
Posted in FreeBSD, Linux, Linux and FreeBSD Desktop, Linux Audio & Video, Various | 2 Comments »

Convert Windows / MS-DOS end of line characters (CR/LF) to UNIX (LF) with sed

Tuesday, November 29th, 2011

I guess everyone has ended up with problems into a script files written under Windows using some text editor which incorrectly placed into the end of lines Windows (rn) end of lines instead of the UNIX (r).
Those who have have already take advantage of the nice tiny utility dos2unix which is capable of convert the Windows end of lines to UNIX. However some older UNIXes, like SunOS or HP-UX does not have the dos2unix utility into the list of packages one can install or even if its possible to install dos2unix it takes quite a hassle.
In that cases its good to say convertion of end of lines can be done without using external end programs by simply using UNIX sed .
The way to remove the incorrect Windows ^M (as seen in unix text editors) is by using the sed one liner:

server# sed 's/.$//' file-with-wrong-windows-eol.txt > file-with-fixed-unix-eol.txt

Tags: , , , , , , , , , , , , , , , , , , , , , , , , ,
Posted in FreeBSD, Linux, System Administration | No Comments »

John McCarthy Creator and Father of Modern Artificial Intelligence and Lisp programming language creator passed away at 84

Wednesday, October 26th, 2011

John McCarthy Creator of Lisp programming language and Invetor of modern Artificial Intelligence

Yesterday night, one more Computer Genius – John McCarthy has passed away at the age of 84.
John McCarthy is mostly famous for the creation of Lisp Programming language, which was probably the most used programming language in the short past. There are plenty of corporate old iron hardwares which still run programs written in Lisp. Lisp is the language in which Richard Stallman has created his so famous EMACS text editor for GNU.

Computer Technology students, should have studied certainly Lisp in the form of Lisp Scheme.
Lisp is the the second oldest high level programming language only to be predeceded by Fortran .
Lisp gave birth to the so called Macro programming languages
and was invented by McCarthy in 1958, while he was in Massachusetts MIT university.
What is so important about Lisp is that it is de-facto the first language in the world which was written to be suitable for AI (Artificial Intelligence) researches. There is plenty of interesting information about Lisp as well as a number of forks and variations circulating for almost all the existing major operating systems nowdays.

Besides LISP creation McCarthy was in the first team who did a the first Remote Computer Chess game. The game played was among USSR and US scientists, where the moves were transferred by telegraph.
In 1972 MCCarthy was awarded with the Turing Award – (Today probably the most prestigious award for incredible technology achievements in the world).
McCarth’s home website had a lot of great papers on programming languages, mathematical theory of computation and most importantly philosophical words and notes on Artificial Intelligence
His site has a lot of his essays as well as his personal views on the world and predictions (foreseen probabilities by him) on the world future.
McCarthy had even written a short Sci-Fi story (The Robot and The Baby), the story aim was to explore the question, whether robots should have simulated emotions.John McCarthy AI later days life picture

John McCarthy is among the brightest computer genius who ever live on this planet as well as a true “icon” for a computer hacker. The news for his death is quite shocking especially after the sudden death of the creator of C programming Language and UNIX Denis Ritchie , and a week earlier the pass of Steve Jobs
It seems like no coincidence, that the brightest computer minds are departuring this life, probably God is taking them one by one just like he gave them the gifts to invent and revolutionize the technology we use today.
Surely McCarthy has left a huge landmark on technology and his name will be in the books for the generations to come.

Tags: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,
Posted in Everyday Life, Programming, Various | 1 Comment »

Develop your children intellect with Gcompris high quality educational software on GNU / Linux, Windows and Mac OS X

Monday, October 3rd, 2011

Gcompris Main entry Screen

Gcompris is a great piece of software to educate children in the age interval of 2 to 10 years old.
Gcompris is a tool of educative and funny interactive computer applications many of which has a form of games.

Gcompris strategy games

Gcompris is teaching the children on the following fields of knowledge:
 

  • understand the computer – keyboard, mouse etc.
  • Algebra – Summing up numbers, enumarations, table memory, mirror image etc.
  • Science – The Canal lock, the water cycle, how a submarine works, elementary electric simulation
  • Geography – Find out about country locations, Place the country on the map
  • Games – Learn how to play chess, improve memory and memorization, sudoku etc.
  • Reading – Learning to read fluent, reading practice
  • Learn to proerply tell time, solve puzzle games and learn famous paintings, basic cartoon making, vector drawing

Gcompris reading activities

All the funny activities Gcompris educative kid tool offers 100+. Gcompris is in active development so with time more and more activities gets added.
Gcompris is a Free Software and among with its native GNU / Linux support it has ports for Windows and Mac OS X

The Free Software nature of Gcompris gives possibility to be easily adapted and further developed! Its really funny not only for kids, but even for adults. If you had a stressy day and you want to relax in a childish way and feel like a kid again, give it a try and you will be amazed how much light and happiness this computer program can bless you with 😉

Many of Gcompris activities has a little cute penguins and in general its capable of introducing the kids to the nice concept of the free software.

As a free software Gcompris is really great as among the rest of the so popular free software freedoms: to distribute and modify the software it comes absolutely free of charge (in money terms). This is great news for parents who are growing their kids in the “developing world”, the so called 2nd and 3rd world as well is a good alternative to the many available paid costly application and games aiming at kids brain development.
Gcompris puzzle games

The name Gcompris is also known in free software realm under the name I GOT IT .Gcompris has currently Sound and text support for 33 Country Languages, here is a completele list of languages currently supported:

Arabic, Asturian, Bulgarian, Breton, Czech, Danish, German, Greek, English, Esperanto, Spanish, Basque, Finnish, French, Hebrew, Indian, Hungarian, Indonesian, Italian, Indian, Norwegian, Dutch, Norwegian, Punjabi, Portuguese, Portuguese, Russian, Somali, Serbian, Swedish, Turkish, Urdu, Chinese

Some of the languages supported still does not have a 100% translation but partially translated as its a question of time that enough translators are found to make the translations for all available major languages. The only 100% completed trasnlation as of time of writting is in French, Slovenian and Spanish

Gcompris is already included in almost all available moderm GNU / Linux distributions. A packaged version of it is part of Fedora, Debian and Ubuntu.

Gcompris Mathematics

For all those parents who wish to educate their children on Fedora Linux install it with the GUI installer or yum with cmd:

[root@fedora ~]# yum install gcompris
...

On Debian and Ubuntu Gcompris is installable via apt from repos:

debian:~# apt-get install gcompris
...

To add a text and sound translation to Gcompris its also necessery to install the relevant gcompris-sound distribution package, for example to add the sound translations for my native Bulgarian language I had to install the package gcompris-sound-bg, e.g.:

debian:~# apt-get install gcompris-sound-bg
...

Gcompris is developed to use the Gnome’s GTK and is a perfect match for Linux users who already run a Gnome Desktop on their PCs.

Most of Gcompris versions should run without much hassle on Mac OS X and Windows so all mommies and daddies on Windows or Mac can install it and use it to educate their kids 😉

Here are few more screenshots of Gcompris

Gcompris children intellect develop Experimental activities

Gcompris educational kids develop intellect Discovery activities
Gcompris various games for develop your kid intellect
Gcompris also fits well with  Tux for Kids Linux / Windows ready games also suitable for kids development. Gcompris and Tux for Kids makes Linux and  free software more “children mature” and is a perfect to be used on kids educational computers in kindergartens or any educational institutions aiming at children development. 

To sum it up, if you want to make your children smarter or you’re bored to death and you need to have some rest by going back to your childhood years give gcompris a try 😉

Tags: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,
Posted in Entertainment, Games Linux, Linux, Various, Windows | 1 Comment »

Using perl and sed to substitute strings in multiple files on Linux and BSD

Friday, August 26th, 2011

Using perl and sed to replace strings in files on Linux, FreeBSD, OpenBSD, NetBSD and other UnixOn many occasions when had to administer on Linux, BSD, SunOS or any other *nix, there is a need to substitute strings inside files or group of files containing a certain string with another one.

The task is not too complex and many of the senior sysadmins out there would certainly already has faced this requirement and probably had a good idea on files substitution with perl and sed, however I’m quite sure there are dozen of system administrators out there who did not know, how and still haven’t faced a situation where there i a requirement to substitute from a command shell or via a scripting language.

This article tagets exactly these system administrators who are not 100% sys op Gurus 😉

1. Substitute text strings inside files on Linux and BSD with perl

Perl programming language has originally been created to do a lot of text manipulation as well as most of the Linux / Unix based hosts today have installed working copy of perl , therefore using perl as a mean to substitute one string in a file to another one is maybe the best way to completet the task.
Another good thing about perl is that text processing with it is said to be in most cases a bit faster than sed .
However it is still dependent on the string to be substituted I haven’t done benchmark tests to positively say 100% that always perl is quicker, however my common sense suggests perl will be quicker.

Now enough talk here is a very simple way to substitute a reoccuring, text string inside a file with another chosen one is like so:

debian:~# perl -pi -e 's/foo/bar/g' file1 file2

This will substitute the string foo with bar everywhere it’s matched in file1 and file2

However the above code is a bit “dangerous” as it does not preserve a backup copy of the original files, where string is substituted is not made.
Therefore using the above command should only be used where one is 100% sure about the string changes to be made.

Hence a better idea whether conducting the text substitution is to keep also the original file backup under a let’s say .bak extension. To achieve that I use perl as follows:

freebsd# perl -i.bak -p -e 's/syzdarma/magdanoz/g;' file1 file2

This command creates copies of the original files file1 and file2 under the names file1.bak and file2.bak , the files file1 and file2 text occurance of strings syzdarma will get substituted with magdanoz using the option /g which means – (substitute globally).

2. Substitute string in all files inside directory using perl on Linux and BSD

Every now and then the there is a need to do manipulations with large amounts of files, I can’t right now remember a good scenario where I had to change all occuring matching strings to anther one to all files located inside a directory, anyhow I’ve done this on a number of occasions.

A good way to do a mass file string substitution on Linux and BSD hosts equipped with a bash shell is via the commands:

debian:/root/textfiles:# for i in $(echo *.txt); do perl -i.bak -p -e 's/old_string/new_string/g;' $i; done

Where the text files had the default txt file extension .txt

Above bash loop prints each of the files located in /root/textfiles and substitutes everywhere (globally) the old_string with new_string .

Another alternative to the above example to replace multiple occuring text string in all files in multiple directories is possible using a combination of shell commands grep, perl, sort, uniq and xargs .
Let’s say that one wants to match everywhere inside the root directory and all the descendant directories for files with a custom string and substitute it to another one, this can be done with the cmd:

debian:~# grep -R -files-with-matches 'old_string' / | sort | uniq | xargs perl -pi~ -e 's/old_string/new_string/g'

This command will lookup for string old_string in all files in the / – root directory and in case of occurance will substitute with new_string (This command’s idea was borrowed as an idea from http://linuxadmin.org so thx.).

Using the combination of 5 commands, however is not very wise in terms of efficiency.

Therefore to save some system resources, its better in terms of efficiency to take advantage of the find command in combination with xargs , here is how:

debian:~# find / | xargs grep 'old_string' -sl |uniq | xargs perl -pi~ -e 's/old_string/new_string/g'

Once again the find command example will do exactly the same as the substitute method with grep -R …

As enough is said about the way to substitute text strings inside files using perl, I will further explain how text strings can be substituted using sed

The main reason why using sed could be a better choice in some cases is that Unices are not equipped by default with perl interpreter. In general the amount of servers who contains installed sed compared to the ones with perl language interpreter is surely higher.

3. Substitute text strings inside files on Linux and BSD with sed stream editor

In many occasions, wether a website is hosted, one needs to quickly conduct a change in string inside all files located in a directory, to resolve issues with static urls directly encoded in html.
To achieve this task here is a code using two little bash script loops in conjunctions with sed, echo and mv commands:

debian:/var/www/website# for i in $(ls -1); do cat $i |sed -e "s#index.htm#http://www.webdomain.com/#g">$i.new; done
debian:/var/www/website# for i in $(ls *.new); do mv $i $(echo $i |sed -e "s#.new##g"); done

The above command sed -e “s#index.htm#http://www.webdomain.com/#g”, instructs sed to substitute all appearance of the text string index.htm to the new text string http://www.webdomain.com

First for bash loop, creates all the files with substituted string to file1.new, file2.new, file3.new etc.
The second for loop uses mv to overwrite the original input files file1, file2, file3, etc. with the newly created ones file1.new, file2.new, file3.new

There is a a way shorter way to conclude the same text substitutions task using a simpler one liner with only using sed and bash’s eval capabilities, here is how:

debian:/var/www/website# sed -i 's/old_string/new_string/g' *

Above command will change old_string to new_string inside all files in directory /var/www/website

Whether a change has to be made with less than 1024 files using this method might be more efficient, however whether a text substitute has to be done to let’s say 5000+ the above simplistic version will not work. An error of Argument list too long will prevent the sed -i ‘s/old_string/new_string/g’ to complete its task.

The above for loop 2 liner should be also working without problems with FreeBSD and the rest of BSD derivatives, though I have not tested it yet, hence any feedback from FreeBSD guys is mostly welcome.

Consider that in order to have the for loops commands work on FreeBSD or NetBSD, they have to be run under a bash shell.
That’s all folks thanks the Lord for letting me write this nice article, I hope it gives some insights on how multiple files text replace on Unix works .
Cheers 😉

Tags: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,
Posted in FreeBSD, Linux, System Administration, Web and CMS | 1 Comment »

How to add a range of virtual IPs to a CentOS and Fedora Linux server

Monday, July 18th, 2011

Recently I had the task to add a range of few IP addresses to as a virtual interface IPs.

The normal way to do that is of course using the all well known ifconfig eth0:0, ifconfig eth0:1 or using a tiny shell script which does it and set it up to run through /etc/rc.local .

However the Redhat guys could omit all this mambo jambo and do it The Redhat way TM 😉 by using a standard method documented in CentOS and RHEL documentation.
Here is how:

# go to network-script directory[root@centos ~]# cd /etc/sysconfig/network-scripts
# create ifcfg-eth0-range (if virtual ips are to be assigned on eth0 lan interface[root@centos network-scripts]# touch ifcfg-eth0-range

Now inside ifcfg-eth0-range, open up with a text editor or use the echo command to put inside:

IPADDR_START=192.168.1.120
IPADDR_END=192.168.1.250
NETMASK=255.255.255.25
CLONENUM_START=0

Now save the /etc/sysconfig/network-scripts/ifcfg-eth0-range file and finally restart centos networking via the network script:

[root@centos network-scripts]# service network restart

That’s all now after the network gets reinitialized all the IPs starting with 192.168.1.120 and ending in 192.168.1.250< will get assigned as virtual IPs for eth0 interface
Cheers 😉

Tags: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,
Posted in Linux and FreeBSD Desktop, System Administration | No Comments »

How to check Host is up with Nagios for servers with disabled ICMP (ping) protocol

Friday, July 15th, 2011

At the company where I administrate some servers, they’re running Nagios to keep track of the servers status and instantly report if problems with connectivity to certain servers occurs.

Now one of the servers which had configured UP host checks is up, but because of heavy ICMP denial of service attacks to the servers the ICMP protocol ping is completely disabled.

In Nagios this host was constantly showing as DOWN in the usual red color, so nagios reported issue even though all services on the client are running fine.

As this is quite annoying, I checked if Nagios supports host checking without doing the ICMP ping test. It appeared it does through something called in nagios Submit passive check result for host

Enabling the “Submit passive check result for this host” could be done straight from Nagios’s web interface (so I don’t even have to edit configurations! ;).
Here is how I did it. In Nagios I had to navigate to:

Hosts -> Click over my host (hosting1) which showed in red as down

Nagios disable ICMP ping report for hosts

You see my down host which I clicked over showing in red in above pic.

On next Nagios screen I had to select, Disable active checks of this host

Nagios Disable active ICMP checks of this host
and press on the Commit button.

Next following text appears on browser:

Your command request was successfully submitted to Nagios for processing.

Note: It may take a while before the command is actually processed.

Afterwards I had to click on Submit passive check result for this host and in:
Check Output to type in:

check_tcp -p 80

Here is the Screenshot of the Command Options dialog:

Nagios submit passive check with check TCP -p 80

That’s all now Nagious should start checking the down host by doing a query if the webserver on port 80 is up and running instead of pinging it.
As well as the server is no longer shown in the Nagio’s Down host list.

Tags: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,
Posted in Linux, System Administration | 4 Comments »

What is Xorg’s server DPMS module for? And how to use it to reduce your computer power consumption

Thursday, April 21st, 2011

As I’m manually configuring a Xserver via xorg.conf I have noticed a block of code in:

Section "Monitor"
Identified "Generic Monitor"
Option "DPMS"
EndSection That triggered my curiousity to research further what is DPMS . A very quick google search revealed that DPMS’s purpose is to communicate to communicate between the monitor and the computer, to make the computer turn off the (CRT or LED) based monitor if the computer is not used

Thus in short to rephrase DPMS is a power saving handy Xorg feature. I many custom configured xorg.conf like the mine I’m building right now does not include DPMS as many people doesn’t have idea what DPMS is and how to enable it.

DPMS is also an interface to the Energy start power-saving capability if not all, most of the modern day monitor screens.

DPMS enables the Xserver to control automatically the computer screen and thus reduces the overall computer power consumption.

To enable the use of DPMS on my Linux, all I had to do is place a couple of configuration directives in my xorg.conf .:
Here is how I enabled DPMS in my Xorg server:

1. Edit with a text editor /etc/X11/xorg.conf

2. Find the Monitor Section , e.g.:

Section "Monitor"
....
EndSection

3. Add inside the Monitor Section Options "DPMS" "true"

4. Lookup for the ServeryLayout section , e.g.:

Section "ServerLayout"
...
EndSection

5. Place inside the ServerLayout section For instance the following options:

Option "StandbyTime" "20"
Option "SuspendTime" "10"
Option "OffTime "25"

You might like to change the options StandbyTime, SuspendTIme or OffTime to match your likings.
6. As a last step restart the Xorg server.

Press Ctrl+Alt+BackSpace or by issuing:

host:~# pkill -HUP X

Test that DPMS is loaded properly by reviewing /var/log/Xorg.0.log for example:

host:~# grep -i /var/log/Xorg.0.log
(II) Loading extensions DPMS

Tags: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,
Posted in Linux, Linux and FreeBSD Desktop, Linux Audio & Video | No Comments »

« Older Entries
Newer Entries »