Create pdf with pictures (one in each page) using tex

% Document type
\documentclass{article}

% Including required packages
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{latexsym}
\usepackage{graphicx}

% Setup the page type and margin
\topmargin -1.5in
\oddsidemargin -1.0in
\evensidemargin -1.0in
\pagestyle {empty}

% Begining of the document
\begin{document}

% Picture on the first page 
\begin{figure}
  \centering
  \includegraphics[width=8.5in, height=11in, angle=0]{Picture01.jpg}
\end{figure}

% Picture on the secoond page
\newpage
\begin{figure}
  \centering
  \includegraphics[width=8.5in, height=11in, angle=0]{Picture02.jpg}
\end{figure}

% You can add more pages with pictures...

% End of the document
\end{document}

Create daemon process in C

#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <syslog.h>
#include <string.h>

#define LOCKFILE "/var/lock/PROCESSNAME"

#ifdef CREATE_PID_FILE
#define PIDFILE "/var/run/PROCESSNAME.pid"
#endif

void deamon (void)
{
  pid_t pid, sid;
#ifdef CREATE_PID_FILE
  pid_t child;
  FILE *pidfp = NULL;
#endif  
  int lockfd = -1;

  /* Create the lock file */
  lockfd = open (LOCKFILE, O_RDWR | O_CREAT | O_EXCL, 0640);
  if (-1 == lockfd)
  {
    syslog (LOG_ERR, "ERROR: Unable to create lock file [" LOCKFILE "] -> %s.", strerror(errno));
    if (EEXIST == errno)
    {
      syslog (LOG_ERR, "ERROR: Another instance of this process might be already running. "
              "Please kill that process or delete the lock file and try again.");
      exit (EXIT_FAILURE);
    }
  }
  
  /* Fork the child */
  pid = fork();
  if (-1 == pid)
  {
    syslog (LOG_ERR, "ERROR: Unable to fork the child process -> %s.", strerror(errno));

    /* On failure, delete the lock file */
    if (-1 == unlink (LOCKFILE))
    {
      syslog (LOG_ERR, "ERROR: Unable to delete the lock file [" LOCKFILE "] -> %s.", strerror(errno));
    }

    exit (EXIT_FAILURE);
  }

  /* Exit from the parent */
  if (0 != pid)
  {
    exit (EXIT_SUCCESS);
  }

#ifdef CREATE_PID_FILE
  child = getpid();

  pidfp = fopen (PIDFILE, "w");
  if (NULL == pidfp)
  {
    syslog (LOG_ERR, "ERROR: Unable to open the pid file [" PIDFILE "] -> %s", strerror(errno));
    
    /* On failure, delete the lock file */
    if (-1 == unlink (LOCKFILE))
    {
      syslog (LOG_ERR, "ERROR: Unable to delete the lock file [" LOCKFILE "] -> %s.", strerror(errno));
    }

    exit (EXIT_FAILURE);
  }

  fprintf (pidfp, "%d\n", child);
  fclose (pidfp);
#endif

  /* Make the child as the leader of the process */
  sid = setsid ();
  if ((pid_t)-1 == sid)
  {
    syslog (LOG_ERR, "ERROR: Unable to create new seesion -> %s", strerror(errno));

    /* On failure, delete the lock file and pid file */
    if (-1 == unlink (LOCKFILE))
    {
      syslog (LOG_ERR, "ERROR: Unable to delete the lock file [" LOCKFILE "] -> %s.", strerror(errno));
    }

#ifdef CREATE_PID_FILE
    if (-1 == unlink (PIDFILE))
    {
      syslog (LOG_ERR, "ERROR: Unable to delete the lock file [" PIDFILE "] -> %s.", strerror(errno));
    }
#endif

    exit (EXIT_FAILURE);
  }

  /* Set the calling process's file mode creation mask */
  umask (0);

  /*
   * Changing working directory to '/' to make sure that
   * the process does not depend on any mounted partition
   * execpt the root of the filesystem
   */
  if(-1 == chdir ("/"))
  {
    syslog (LOG_ERR, "ERROR: Unable to change the directory to \"/\" -> %s", strerror(errno));

    /* On failure, delete the lock file and pid file */
    if (-1 == unlink (LOCKFILE))
    {
      syslog (LOG_ERR, "ERROR: Unable to delete the lock file [" LOCKFILE "] -> %s.", strerror(errno));
    }

#ifdef CREATE_PID_FILE
    if (-1 == unlink (PIDFILE))
    {
      syslog (LOG_ERR, "ERROR: Unable to delete the lock file [" PIDFILE "] -> %s.", strerror(errno));
    }
#endif

    exit (EXIT_FAILURE);
  }

  /* Close standard input file descriptor */
  close (0);

  /* Redirect standard output and errror to /dev/null */
  freopen ( "/dev/null", "w", stdout);
  freopen ( "/dev/null", "w", stderr);

}

Reference: http://www.netzmafia.de/skripten/unix/linux-daemon-howto.html

Create daemon process in Python

#!/usr/bin/env python
# Filename: daemon.py

# Make the process to run in the background.

__author__ = "Karthikeyan Periasamy"
__version__ = "0.1"
__all__ = ["daemonize"]

# Standard modules
import os               # OS interface functions.
import sys              # System specific functions.
from syslog import *    # Logging functions.

# Daemon parameters
UMASK = 0       # File mode creation mask for the calling process 
WORKDIR = "/"   # The Working directory

# Find the null device /dev/null
if (hasattr(os, "devnull")):
    NULL_DEVICE = os.devnull
else:
    NULL_DEVICE = "/dev/null"
    
# Function
def daemonize (procname):
    openlog (procname, LOG_PID)
    
    try:
        # Fork the child
        syslog (LOG_INFO, "Daemizing")
        syslog (LOG_INFO, "Creating the first child")
        pid = os.fork ()
        
        # Exit from the parent
        if 0 != pid:
            syslog (LOG_INFO, "Parent exiting")
            os._exit (0)

        # Make the child as the leader of the process
        syslog (LOG_INFO, "Child created")
        syslog (LOG_INFO, "Creating a new session")
        os.setsid ()

        # Fork a child again to make sure that no terminal device is connected to it.
        syslog (LOG_INFO, "Creating the second child")
        pid = os.fork ()

        # Exit from the first child
        if 0 != pid:
            syslog (LOG_INFO, "First child exiting")
            os._exit (0)

        # Set the calling process's file mode creation mask
        syslog (LOG_INFO, "Set the calling process's file mode creation mask")
        os.umask (UMASK)

        # Changing working directory to '/' to make sure that
        # the process does not depend on any mounted partition
        # execpt the root of the filesystem
        logmsg = 'Changing working directory to "' + WORKDIR + '" to avoid dependencies'
        syslog (LOG_INFO, logmsg)
        os.chdir (WORKDIR)

        # Close standard input, output and error file descriptors
        syslog (LOG_INFO, "Closing I/O file descriptors")
        os.close (0)
        os.close (1)
        os.close (2)

        # Redirect standard output and errror to /dev/null
        os.open(NULL_DEVICE, os.O_RDWR)
        os.dup2(0, 1)
        os.dup2(0, 2)

    except:
        logmsg = "Unexpected error:" + repr (sys.exc_info()[1])
        syslog (LOG_ERR, logmsg)
        os._exit (1)


# ---------------------------------------------------------------------------
# Main program (for testing)
# ---------------------------------------------------------------------------

if __name__ == '__main__':

    daemonize("daemon_test")
    syslog(LOG_INFO, 'Daemon is sleeping for 10 seconds')

    import time
    for i in range (10):
        syslog(LOG_INFO, 'Sleeping...')
        time.sleep(1)

    syslog(LOG_INFO, 'Daemon exiting')
    sys.exit(0)

Reference: http://code.activestate.com/recipes/278731-creating-a-daemon-the-python-way/

Reading and Writing to Excel Spreadsheets in Python

I find it useful.
excel-spreadsheets-and-python

Script to log stepwise execution and output of another bash script into syslog

The input arguments for this script would be another script with its input arguments. First, this script stores the stepwise execution and the output of the called bash script into a temporary file. When the called bash script finishes its execution, this script reads the temporary file and logs them into syslog. We are using a temporary file because if we pipe the output of the called script we will lose the true return value of that script.

#!/bin/bash

tmpfile=$(mktemp)
(/bin/bash -x $@ 2>&1) > $tmpfile
retval=$?
cat $tmpfile | logger -t "logger [$1]"
rm -f $$tmpfile

exit $retval
   
  

Display code blocks on web page

In my blog, almost all my posts have some code blocks. Whenever I tried to post some code, I had greate difficulties to show the code blocks on the web page as how it should be on the normal editor. Later I realized that we can do it easily with the help of <pre> tag and some more changes and here is the script to do that some more.

#!/bin/bash
usage ()
{
    cat <<EOF
Usage: $(basename $0) <code file>
EOF
exit 1;
}

# Check for the input argument
if [ $# -ne 1 ]; then
    usage
fi

if [ ! -e "$1" ]; then
    echo "ERROR: File ($1) does not exist"
    exit 1
fi

cat <<EOF
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<title>$1.html</title>
<meta content="MSHTML 6.00.6000.17023" name="GENERATOR">
<meta http-equiv="Content-Type" content="text/html; charset=unicode">
</head>
<body>
<pre>
EOF

sed -e 's/\&/\&amp;/g' -e 's/\"/\&quot;/g' -e 's/˜/\&tilde;/g' -e 's/>/\&gt;/g' -e 's/</\&lt;/g' $1

cat <<EOF
</pre>
</body>
</html>
EOF

Script to mount partitions from image file in linux

#!/bin/bash

usage ()
{
    cat <<EOF
Usage: $(basename $0) <image file>
EOF
exit 1;
}

# Check for the input argument
if [ $# -ne 1 ]; then
    usage
fi

sfdisk -l -uS $1 

sfdisk -l -uS $1 2>/dev/null | awk '
           BEGIN {
             i = 1
           }
           /sectors\/track$/ {
             split ($2, array, ":"); 
             imagefile = array[1];
           }
           /^Units = sectors of/ {
             secsize = $5;
           }
           !/#sectors|sectors\/track$|^$|^Units = sectors of/ && $4 != 0 {
             partoffset = secsize * $2;
             cmd = sprintf ("test -e /mnt/tttt%d", i);
             cmd1 = sprintf ("test -d /mnt/tttt%d", i);
             if (system (cmd) != 0)
             {
               cmd = sprintf ("mkdir /mnt/tttt%d 2>/dev/null", i);
               if (system (cmd) != 0)
               {
                 printf ("Error: Could not create the director /mnt/tttt%d.Please try with root privilege.\n", i);
                 exit;
               }
             }
             else if (system (cmd) != 0)
             {
               printf ("Error: /mnt/tttt%d is not a directory.\n", i);
               exit;
             }
             cmd = sprintf ("mount -o loop,offset=%d %s /mnt/tttt%d", partoffset, imagefile, i); 
             if (system (cmd) != 0)
             {
               exit;
             }
             printf ("Mounting: %s ---> /mnt/tttt%d\n", $1, i);
             i++;
           }'

  To run this script:
  root@ubuntu:~# mountImageFile.sh <image file>

  Run this script with root privilege.

Note: This script will not work for large partitions because of the limitation in sfdisk.
Reference: http://lists.samba.org/archive/linux/2005-April/013444.html & manpages awk and sfdisk