Category Archives: Programming

programming

Working with node.js and nodemon – part 001

Node.js is a platform for easily building fast, scalable network applications. Download the archive from here. Unarchive and you can use it.

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[free-tutorials@free-tutorials ~]$ cd node-v0.10.10-linux-x86/
[free-tutorials@free-tutorials node-v0.10.10-linux-x86]$ ls
bin  ChangeLog  lib  LICENSE  README.md  share

The nodemon can be used during the development of a node.js based application. How? will watch the files in the directory that nodemon was started. Also, it will automatically restart your node… Read More »

How to reset django or create another superuser.

If you know your username (for example admin) then use this:

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manage.py changepassword admin

Also, You may try through the console to see and change the password: Use the shell console and start the Django shell:

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python manage.py shell

Now use this Django script:

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from django.contrib.auth.models import User
User.objects.filter(is_superuser=True)
u = User.objects.get(username='your username')
u.set_password('raw password')
u.save()

If you need to create another superuser.

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13:56 ~/mysite $ python manage.py createsuperuser
Username: testsuper
E-mail address: testsuper@mail.com
Password:
Password (again):
Superuser created successfully.

How to get? the GLSL and OpenGL version.

You can get a version from the OpenGL and GL Shading program by:

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glGetString(GL_SHADING_LANGUAG­E_VERSION)

If don’t initialize the OpenGL you can get it:

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OpenGL (null), GLSL (null)

Let’s try one simple example.

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#include <GL/glut.h>
#include
// define the size of the window
#define window_width  640
#define window_height 480
// Main loop function
void main_loop_function()
{
// Clear color screen
// And depth , is used internally to block obstructed objects
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// If don't use the next source code OpenGL will show dizzy content of windows
glutSwapBuffers();
}
// Initialze OpenGL perspective matrix
void GL_Setup(int width, int height)
{
glViewport( 0, 0, width, height );
glMatrixMode( GL_PROJECTION );
glEnable( GL_DEPTH_TEST );
gluPerspective( 45, (float)width/height, .1, 100 );
glMatrixMode( GL_MODELVIEW );
}
// Initialize GLUT and start main loop function
int main(int argc, char** argv) {
glutInit(&argc, argv);
glutInitWindowSize(window_width, window_height);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
glutCreateWindow("www.free-tutorials.org - get? the GLSL version example.");
glutIdleFunc(main_loop_function);
GL_Setup(window_width, window_height);
//next source code will show on shell the OpenGL and GLSL version
printf("OpenGL %s, GLSL %s\n", glGetString(GL_VERSION),glGetString(GL_SHADING_LANGUAGE_VERSION));
glutMainLoop();
}

The output will be print on the shell.

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OpenGL 2.1 Mesa 7.3-devel, GLSL 1.10

Using standard C library sysconf .

Using standard C library sysconf is very simple. See all about sysconf.

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NAME
     sysconf -- get configurable system variables
 
LIBRARY
     Standard C Library (libc, -lc)
 
SYNOPSIS
     #include
 
     long
     sysconf(int name);
 
DESCRIPTION
     This interface is defined by IEEE Std 1003.1-1988 (``POSIX.1'').  A far
     more complete interface is available using sysctl(3).
 
     The sysconf() function provides a method for applications to determine
     the current value of a configurable system limit or option variable.  The
     name argument specifies the system variable to be queried.  Symbolic con-
     stants for each name value are found in the include file .
     Shell programmers who need access to these parameters should use the
     getconf(1) utility.
 
     The available values are as follows:
 
     _SC_ARG_MAX
     The maximum bytes of argument to execve(2).
 
     _SC_CHILD_MAX
     The maximum number of simultaneous processes per user id.
 
     _SC_CLK_TCK
     The frequency of the statistics clock in ticks per second.
 
     _SC_IOV_MAX
     The maximum number of elements in the I/O vector used by
     readv(2), writev(2), recvmsg(2), and sendmsg(2).
 
     _SC_NGROUPS_MAX
     The maximum number of supplemental groups.
 
     _SC_NPROCESSORS_CONF
     The number of processors configured.
 
     _SC_NPROCESSORS_ONLN
     The number of processors currently online.
 
     _SC_OPEN_MAX
     The maximum number of open files per user id.
 
     _SC_PAGESIZE
     The size of a system page in bytes.
 
     _SC_STREAM_MAX
     The minimum maximum number of streams that a process may have
     open at any one time.
 
     _SC_TZNAME_MAX
     The minimum maximum number of types supported for the name of a
     timezone.
 
     _SC_JOB_CONTROL
     Return 1 if job control is available on this system, otherwise
     -1.
 
     _SC_SAVED_IDS
     Returns 1 if saved set-group and saved set-user ID is available,
     otherwise -1.
 
     _SC_VERSION
     The version of IEEE Std 1003.1 (``POSIX.1'') with which the sys-
     tem attempts to comply.
 
     _SC_BC_BASE_MAX
     The maximum ibase/obase values in the bc(1) utility.
 
     _SC_BC_DIM_MAX
     The maximum array size in the bc(1) utility.
 
     _SC_BC_SCALE_MAX
     The maximum scale value in the bc(1) utility.
 
     _SC_BC_STRING_MAX
     The maximum string length in the bc(1) utility.
 
     _SC_COLL_WEIGHTS_MAX
     The maximum number of weights that can be assigned to any entry
     of the LC_COLLATE order keyword in the locale definition file.
 
     _SC_EXPR_NEST_MAX
     The maximum number of expressions that can be nested within
     parenthesis by the expr(1) utility.
 
     _SC_LINE_MAX
     The maximum length in bytes of a text-processing utility's input
     line.
 
     _SC_RE_DUP_MAX
     The maximum number of repeated occurrences of a regular expres-
     sion permitted when using interval notation.
 
     _SC_2_VERSION
     The version of IEEE Std 1003.2 (``POSIX.2'') with which the sys-
     tem attempts to comply.
 
     _SC_2_C_BIND
     Return 1 if the system's C-language development facilities sup-
     port the C-Language Bindings Option, otherwise -1.
 
     _SC_2_C_DEV
     Return 1 if the system supports the C-Language Development Utili-
     ties Option, otherwise -1.
 
     _SC_2_CHAR_TERM
     Return 1 if the system supports at least one terminal type capa-
     ble of all operations described in IEEE Std 1003.2 (``POSIX.2''),
     otherwise -1.
 
     _SC_2_FORT_DEV
     Return 1 if the system supports the FORTRAN Development Utilities
     Option, otherwise -1.
 
     _SC_2_FORT_RUN
     Return 1 if the system supports the FORTRAN Runtime Utilities
     Option, otherwise -1.
 
     _SC_2_LOCALEDEF
     Return 1 if the system supports the creation of locales, other-
     wise -1.
 
     _SC_2_SW_DEV
     Return 1 if the system supports the Software Development Utili-
     ties Option, otherwise -1.
 
     _SC_2_UPE
     Return 1 if the system supports the User Portability Utilities
     Option, otherwise -1.
 
     These values also exist, but may not be standard:
 
     _SC_PHYS_PAGES
     The number of pages of physical memory.  Note that it is possible
     that the product of this value and the value of _SC_PAGESIZE will
     overflow a long in some configurations on a 32bit machine.

The source code is this:

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#include
#include
 
main() {
long tmp,tmp2;
tmp=sysconf(_SC_NPROCESSORS_CONF);
tmp2=sysconf(_SC_CLK_TCK);
if(tmp==-1 && tmp2==-1)
        printf("Check the argument passed to sysconf");
else
 
printf("Processors : %d \n",tmp);
 
printf("Clock ticks/second: %d \n",tmp2);
}

I use stdio.h and unistd.h libs. Also, I have two vars tmp and tmp2. This vars will take the result of _SC_NPROCESSORS_CONF and _SC_CLK_TCK using sysconf. Use the gcc to make binary.

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$ gcc  sysconf-test.c -o sysconf-test

… run it… Read More »

Linux .bashrc to extract many archives

This is just a new function to uncompressing many files like: .tar.bz2,.tar.gz,.bz2,.rar,.gz,.tar,.tbz2,.tgz,.zip,.Z,.7z Open .bashrc file from home/user folder. With your text editor and add the next function on the end of the file.

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function unarchive()      
{
    if [ -f $1 ] ; then
        case $1 in
            *.tar.bz2)   tar xvjf $1     ;;
            *.tar.gz)    tar xvzf $1     ;;
            *.bz2)       bunzip2 $1      ;;
            *.rar)       unrar x $1      ;;
            *.gz)        gunzip $1       ;;
            *.tar)       tar xvf $1      ;;
            *.tbz2)      tar xvjf $1     ;;
            *.tgz)       tar xvzf $1     ;;
            *.zip)       unzip $1        ;;
            *.Z)         uncompress $1   ;;
            *.7z)        7z x $1         ;;
            *)           echo "'$1' cannot be extracted via >unarchive<" ;;
        esac
    else
        echo "'$1' is not a valid file!"
    fi
}

Open a new terminal. This will work with the new function from .bashrc.

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$ unarchive glib-2.30.2.tar.bz2

Alice – 3D educational programming environment – installation .

What is Alice? The www.alice.org – official website provides a quick introduction. Using an innovative 3D programming environment that makes it easy to create animations or games, the Alice Project seeks to provide tools and materials for a conceptual core of computational thinking, problem-solving, and computer programming. The Alice Suite of educational tools is designed… Read More »