How to use "Like" and "In" together in MySQL ?

Simple and very useful:

SELECT * FROM tablename WHERE column LIKE 'M510%' OR column LIKE 'M615%' OR column LIKE 'M515%' OR column LIKE 'M612%';

Constructor overloading in Perl

Base Class:
-----------

#!/usr/bin/perl
use strict;
use Data::Dumper;

#write package name:
package Person;

#write constructor
sub new
{
#declare => hash & bless it and return it.
my($class)=shift;
my($self)={
        _name=>shift,
        _sname=>shift,
};
bless $self, $class;
return $self;
}

1;
 
Derived class:
--------------

#!/usr/bin/perl

#define package:
package Employee;

use strict;
use Data::Dumper;

#use parent class
use Person;

#Define ISA
our @ISA = qw(Person);

#Define constructor with child and parent both:
sub new
{
my($class)=@_;
my($self)=$class->SUPER::new($_[1],$_[2]);
$self->{_id} = $_[3];
$self->{_sal} = $_[4];

return ($self);
}

1;

Program:
--------

use strict;
use Data::Dumper;

use Person;
use Employee;

sub main
{
my($obj)=Employee->new("mandar","pande","111515","1");
print "$obj->{_name}\n";
print "$obj->{_sname}\n";
print "$obj->{_id}\n";
print "$obj->{_sal}\n";
}

main();

Multithreading in Perl

Found few good links with examples:

http://pages.swcp.com/~breadfan/threads/threads_shared.html

http://migo.sixbit.org/papers/Perl_Threads/slide-00.html

Awesome use case for tr command.
Use case : Remove all whitespaces but one from the output of any of the unix command ( for e. g. free -m )

Current command output:
[root@host ~]free -m
                    total       used       free     shared    buffers     cached
Mem:         16046      15779        267          0         20      14269
-/+ buffers/cache:       1489      14557
Swap:         4000          0       4000


with tr,
[root@host ~]free -m |tr -s " "
 total used free shared buffers cached
Mem: 16046 15778 268 0 20 14269
-/+ buffers/cache: 1488 14558
Swap: 4000 0 4000

where,
-s : replace each input sequence of a repeated character that is listed  in  SET1( in our case it is space character " " ) with a single occurrence of that character.

In this way we can get output with only one space character as a delimiter.

How to execute a script with exit status from bash shell in background ?
=>
[root@host ~]cat /tmp/a
#!/bin/bash
sleep 1
echo 1% complete
sleep 1
echo 10% complete
sleep 1
echo 100% complete
exit 12

[root@host~] (/tmp/a > /tmp/stdout;echo $? > /tmp/ret) &

Verification :
========
[root@puneoshub ~](/tmp/a > /tmp/stdout;echo $? > /tmp/ret) & <----------- way to execute.
[1] 24110
[root@puneoshub ~]
[1]+  Done                    ( /tmp/a > /tmp/stdout; echo $? > /tmp/ret )
[root@puneoshub ~]cat /tmp/stdout /tmp/ret
1% complete < ----- STDOUT
10% complete
100% complete
12 < ----- RETURN

Perl Regex continue......

In order to match a string in a multiline string use the 'm' modifier.

For Ex:
The string is: "Hello wassup\n How u doing\n goaway"

and we have to match "How u doing", it cant be match the same way as perl doesn't check after newline if we dont tell it to.

So use:
$string =~ /How u doing/m

Continue with the perl regex ....... cheers!!!

PERL regex

Removing blank lines: next if ($line =~ /^$/)

Just creating a post for regex !

MySQL Benchmark

How my server is performing ?
===========================

No matter the result of the expression, the result of benchmark() will always be 0. The purpose of benchmark() is not to retrieve the result of the expression but to see how long it takes to repeat the expression for a specific number of times. For example, the following command executes the expression 10 + 10 one million times:

mysql> SELECT BENCHMARK(1000000,10+10);
+--------------------------+
| BENCHMARK(1000000,10+10) |
+--------------------------+
|            0 |
+--------------------------+
1 row in set (0.14 sec)

Identify if a host is UNIX,WIN or ESX.

Nmap string:

nmap -n -P0 -sT -p 111,139,445,514,5989

1.  If Port 111 or 514 is “open”, then UNIX

2.  If Port 139 or 445 is open, then WINDOWS

3.  If Port 5989 is open, then ESX

Netbackup/Storage concepts

Found good link :
http://storagesavvy.com/tag/netbackup/

Netbackup/Storage concepts

Found good link :
http://storagesavvy.com/tag/netbackup/

Comparison of Different SQL Implementation

Guys,
Found a comprehensive research.
Check out this article, it expalins quite interesting things about diff DB's and also a comparison between them, which is a most faq in interviews.

http://troels.arvin.dk/db/rdbms/