^M: not found error in unix

^M: not found error in unix

 I was executing a shell script file through the nohup command. while executing the file i got the ^M: not found error in unix command prompt.

Then i started searching why i am getting this error. after making several googling, i got to know that this is due to i created this shell script file in windows (eclipse) OS. 

Normally when we create any file in windows and move/upload it to unix it append ^M in every line in the unix platform. it causes the error. now you need to remove these ^M character from the  shell script to work it properly. You can do that i several ways

1. opening the script file VI editor and manually removing these extra charactors

2. using dos2unix command

3.....

Date and Time matching in Where clause in Oracle

Date and Time matching in Where clause in Oracle:

It is trick when you want to match date or  date and time in where clause of you oracle sql query.
some time the original field may will be in date, time or some other field. and when you will put date type data with different format in where clause of you sql query it will mismatch and will not provide you the result you want.

You can avoid this kind of problem by using the to_date(date, format) in you where clause and the original field name as usual.

Below is an example:

select *
from table_name
where assoc_id = '6492349324'
and begin_date = TO_DATE('01-APR-2012', 'DD-MON-YYYY')  --what ever will be the data type of begin_date
and end_date = TO_DATE('01-JUL-2012', 'DD-MON-YYYY')    --the query will only match the date out of it


In the above query any date type data can be matched.

Passing Objects as parameters in PHP

Objects are Passed by reference by default:

By default the php objects are passed by reference below example will make it more clear. that is why when we copy object it property's are pointing to the same reference

class A {
    public $foo = 1;
} 
$a = new A;$b = $a;     // $a and $b are copies of the same identifier
             // ($a) = ($b) = 
$b->foo = 2;
echo $a->foo."\n";  //this will output 2 as the reference is copied
                    //$a and $b is point to the same location

$c = new A;$d = &$c;    // $c and $d are references
             // ($c,$d) = 
$d->foo = 2;
echo $c->foo."\n";

$e = new A;

function foo($obj) {
    // ($obj) = ($e) = 
    $obj->foo = 2;
}
foo($e);
echo $e->foo."\n";
?>

the output of the above sample example will
2
2
2



/*
 * Created on Oct 24, 2012
 *
 * To change the template for this generated file go to
 * Window - Preferences - PHPeclipse - PHP - Code Templates
 */

 class ClassTesting {
 
  private $foo;
 
  function __construct($foo){
  $this->foo = $foo;
  }
 
  private function ent($foo){
  $this->foo = $foo;
  }
 
  public function ret($obj){
  $obj->foo = 'this';
  var_dump($obj->foo);
  }
 }

 $x = new ClassTesting("man");
 $a = new ClassTesting("dog");
 $x->ret($a);

?>

Log file location in Linux

Linux log file location:


you can find various logs related to the linux in the following folder

/var/log/

Under this there are many files contains different types of logs of the system. like syslog contains system related logs

it looks like below:

• /var/log/message: General message and system related stuff
• /var/log/auth.log: Authenication logs
• /var/log/kern.log: Kernel logs
• /var/log/cron.log: Crond logs (cron job)
• /var/log/maillog: Mail server logs
• /var/log/qmail/ : Qmail log directory (more files inside this directory)
• /var/log/httpd/: Apache access and error logs directory
• /var/log/lighttpd: Lighttpd access and error logs directory
• /var/log/boot.log : System boot log
• /var/log/mysqld.log: MySQL database server log file
• /var/log/secure: Authentication log
• /var/log/utmp or /var/log/wtmp : Login records file
• /var/log/yum.log: Yum log files