How to set alias name for network machines

Simple thing but avoids our repetative daily work.

To set alias name for your frequently used machine.

#Go to /etc/hosts
vi /etc/hosts
#Make an entry for your machine
#IPAddress Hostname Alias
127.0.0.1 connectmachine.com connect
#Restart your network
/etc/rc.d/init.d/network restart

Once it's done. do a ping to check it up

ping connect

How to Change the Timezone in Linux

Changing Timezone in linux.

1) Change to the directory /usr/share/zoneinfo, where you can find list of timezone regions

2) Move your existing time zone
mv /etc/localtime /etc/localtime-old

3) Link the timezone u needed to localtime
ln -sf /usr/share/zoneinfo/America/Pacific /etc/localtime

4) Update the system time by
/usr/bin/rdate -s time-a.nist.gov

5) Set the ZONE entry in the file /etc/sysconfig/clock file (e.g. "America/Los_Angeles")

6) /sbin/hwclock --systohc

Visual block in VI

Do you need to perform multiple line edits at a single stretch.

I came across VISUAL BLOCK in vi editor.

   CTRL + v makes you to enter the visual mode for your file.
   select multiple lines
   SHIFT + i gives you the insert mode
   Enter the text at beginning of the block
   Press ESC twice to apply changes to all lines.

Blogged with the Flock Browser

PERL script for extracting log file based on time

Below code extracts the huge log file based on time frame passed.

#!/usr/bin/perl

use strict;

my $file;
my $times = 0;
my $needed_response_time = 0;
my $start;
my $end;

sub Usage
{
my ($msg) = $_[0];
if ($msg)
{
print STDERR "$msg \n";
}
print STDERR << "EOHELP"
Usage: split_access_log_by_time

options:

-t - :: time interval for which the log is needed
-g :: filter requests greater than the specified response time

example : split_access_log_by_time -t 10:30:32-12:20:22 access_log
example : split_access_log_by_time -g 10 -t 10:30:32-12:20:22 access_log

EOHELP

}

my $i = 0;
while(defined( (my $arg = $ARGV[$i++]) ))
{
if($arg eq '-g')
{
$needed_response_time = $ARGV[$i++];
}
elsif($arg eq '-t')
{
$times = $ARGV[$i++];
}
elsif($arg eq '-h')
{
Usage();
exit 1;
}
else
{
$file = $arg;
last;
}
}

if(!defined($file))
{
Usage("No input file specified");
exit 1;
}

($start, $end) = split('-', $times);
$start = make_seconds(split(':', $start));
$end = make_seconds(split(':', $end));

if ($end < $start)
{
Usage("end time should be greater than start time");
exit 1;
}

# Group requests based on users
open(FILE, $file);
while()
{
my $line = $_;

my @split = split(' ', $line);
my $time = $split[3];
my $response_time = $split[-1];
$time = substr($time, 1);

my @timefields = split(':', $time);

my $hour = $timefields[1];
my $minute = $timefields[2];
my $second = $timefields[3];

#my $time_in_seconds = ($hour * 60 * 60) + ($minute * 60) + $second;
my $time_in_seconds = make_seconds($hour, $minute, $second);
if ($start<=$time_in_seconds && $end>=$time_in_seconds && $response_time >= $needed_response_time)
{
print $line;
}
}

sub make_seconds()
{
(my $hour, my $minute, my $second) = @_;
return ($hour * 60 * 60) + ($minute * 60) + $second;
}

PERL script to combine two csv files

Below script is used to combine two csv files based on the first column. For example, it is assumed both the file has first column related to project names.

#!/usr/bin/perl -w

$FILE1 = $ARGV[0];
$FILE2 = $ARGV[1];
$PROJECTFILE = $ARGV[2];

my %File1Map = ();
my %File2Map = ();

open(FILE1) or die("Could not open $FILE1 file.");
foreach $line () {
# ($Project,$Attachments,$Announcements,$Documents,$Discussions,$Users,$ArtifactTypeCount,$Alm) = split(',',$line);
($Project,$values) = split(',',$line,2);
# my $tempval="$Attachments,$Announcements,$Documents,$Discussions,$Users,$ArtifactTypeCount,$Alm";
my $tempval = $values;
# print "$Project,$values";
$tempval =~ s/\r|\n//g;
$File1Map{"$Project"} = "$tempval";
}

close(FILE1);

open(FILE2) or die("Could not open $FILE2 file.");
foreach $subline() {
($proj,$izcount) = split(',',$subline);
$File2Map{"$proj"}="$izcount";
}

close(FILE2);

open(PROJECTFILE) or die("Could not open $PROJECTFILE file.");
foreach $projname() {
($name,$dummy)=split('\n',$projname);
my $existingValue=$File1Map{"$name"};
my $newValue=$File2Map{"$name"};

if (! defined $existingValue)
{
$existingValue = ",,,,,,,,";
}
if (! defined $newValue)
{
$newValue = "\n";
}

print "" . $name . "," . $existingValue . "," . $newValue;
}