Posts Tagged ‘code’

Adding custom user based host IP aliases load custom prepared /etc/hosts from non root user on Linux – Script to allow define IPs that doesn’t have DNS records to user preferred hostname

Wednesday, April 14th, 2021

Reading Time: 3minutes

adding-custom-user-based-host-aliases-etc-hosts-logo-linux

Say you have access to a remote Linux / UNIX / BSD server, i.e. a jump host and you have to remotely access via ssh a bunch of other servers
who have existing IP addresses but the DNS resolver recognized hostnames from /etc/resolv.conf are long and hard to remember by the jump host in /etc/resolv.conf and you do not have a way to include a new alias to /etc/hosts because you don't have superuser admin previleges on the hop station.
To make your life easier you would hence want to add a simplistic host alias to be able to easily do telnet, ssh, curl to some aliased name like s1, s2, s3 … etc.


The question comes then, how can you define the IPs to be resolvable by easily rememberable by using a custom User specific /etc/hosts like definition file? 

Expanding /etc/hosts predefined host resolvable records is pretty simple as most as most UNIX / Linux has the HOSTALIASES environment variable
Hostaliases uses the common technique for translating host names into IP addresses using either getaddrinfo(3) or the obsolete gethostbyname(3). As mentioned in hostname(7), you can set the HOSTALIASES environment variable to point to an alias file, and you've got per-user aliases

create ~/.hosts file

linux:~# vim ~/.hosts

with some content like:
 

g google.com
localhostg 127.0.0.1
s1 server-with-long-host1.fqdn-whatever.com 
s2 server5-with-long-host1.fqdn-whatever.com
s3 server18-with-long-host5.fqdn-whatever.com

linux:~# export HOSTALIASES=$PWD/.hosts

The caveat of hostaliases you should know is this will only works for resolvable IP hostnames.
So if you want to be able to access unresolvable hostnames.
You can use a normal alias for the hostname you want in ~/.bashrc with records like:

alias server-hostname="ssh username@10.10.10.18 -v -o stricthostkeychecking=no -o passwordauthentication=yes -o UserKnownHostsFile=/dev/null"
alias server-hostname1="ssh username@10.10.10.19 -v -o stricthostkeychecking=no -o passwordauthentication=yes -o UserKnownHostsFile=/dev/null"
alias server-hostname2="ssh username@10.10.10.20 -v -o stricthostkeychecking=no -o passwordauthentication=yes -o UserKnownHostsFile=/dev/null"

then to access server-hostname1 simply type it in terminal.

The more elegant solution is to use a bash script like below:

# include below code to your ~/.bashrc
function resolve {
        hostfile=~/.hosts
        if [[ -f “$hostfile” ]]; then
                for arg in $(seq 1 $#); do
                        if [[ “${!arg:0:1}” != “-” ]]; then
                                ip=$(sed -n -e "/^\s*\(\#.*\|\)$/d" -e "/\<${!arg}\>/{s;^\s*\(\S*\)\s*.*$;\1;p;q}" "$hostfile")
                                if [[ -n “$ip” ]]; then
                                        command "${FUNCNAME[1]}" "${@:1:$(($arg-1))}" "$ip" "${@:$(($arg+1)):$#}"
                                        return
                                fi
                        fi
                done
        fi
        command "${FUNCNAME[1]}" "$@"
}

function ping {
        resolve "$@"
}

function traceroute {
        resolve "$@"
}

function ssh {
        resolve "$@"
}

function telnet {
        resolve "$@"
}

function curl {
        resolve "$@"
}

function wget {
        resolve "$@"
}

 

Now after reloading bash login session $HOME/.bashrc with:

linux:~# source ~/.bashrc

ssh / curl / wget / telnet / traceroute and ping will be possible to the defined ~/.hosts IP addresses just like if it have been defined global wide on System in /etc/hosts.

Enjoy
 

How to debug failing service in systemctl and add a new IP network alias in CentOS Linux

Wednesday, January 15th, 2020

Reading Time: 5minutes

linux-debug-failing-systemctl-systemd-service--add-new-IP-alias-network-cable

If you get some error with some service that is start / stopped via systemctl you might be pondering how to debug further why the service is not up then then you'll be in the situation I was today.
While on one configured server with 8 eth0 configured ethernet network interfaces the network service was reporting errors, when atempted to restart the RedHat way via:
 

service network restart


to further debug what the issue was as it was necessery I had to find a way how to debug systemctl so here is how:

 

How to do a verbose messages status for sysctlct?

 

linux:~# systemctl status network

linux:~# systemctl status network

 

Another useful hint is to print out only log messages for the current boot, you can that with:

# journalctl -u service-name.service -b

 

if you don't want to have the less command like page separation ( paging ) use the –no-pager argument.

 

# journalctl -u network –no-pager

Jan 08 17:09:14 lppsq002a network[8515]: Bringing up interface eth5:  [  OK  ]

    Jan 08 17:09:15 lppsq002a network[8515]: Bringing up interface eth6:  [  OK  ]
    Jan 08 17:09:15 lppsq002a network[8515]: Bringing up interface eth7:  [  OK  ]
    Jan 08 17:09:15 lppsq002a systemd[1]: network.service: control process exited, code=exited status=1
    Jan 08 17:09:15 lppsq002a systemd[1]: Failed to start LSB: Bring up/down networking.
    Jan 08 17:09:15 lppsq002a systemd[1]: Unit network.service entered failed state.
    Jan 08 17:09:15 lppsq002a systemd[1]: network.service failed.
    Jan 15 11:04:45 lppsq002a systemd[1]: Starting LSB: Bring up/down networking…
    Jan 15 11:04:45 lppsq002a network[55905]: Bringing up loopback interface:  [  OK  ]
    Jan 15 11:04:45 lppsq002a network[55905]: Bringing up interface eth0:  RTNETLINK answers: File exists
    Jan 15 11:04:45 lppsq002a network[55905]: [  OK  ]
    Jan 15 11:04:45 lppsq002a network[55905]: Bringing up interface eth1:  RTNETLINK answers: File exists
    Jan 15 11:04:45 lppsq002a network[55905]: [  OK  ]
    Jan 15 11:04:46 lppsq002a network[55905]: Bringing up interface eth2:  ERROR     : [/etc/sysconfig/network-scripts/ifup-eth] Device eth2 has different MAC address than expected, ignoring.
    Jan 15 11:04:46 lppsq002a network[55905]: [FAILED]
    Jan 15 11:04:46 lppsq002a network[55905]: Bringing up interface eth3:  RTNETLINK answers: File exists
    Jan 15 11:04:46 lppsq002a network[55905]: [  OK  ]
    Jan 15 11:04:46 lppsq002a network[55905]: Bringing up interface eth4:  ERROR     : [/etc/sysconfig/network-scripts/ifup-eth] Device eth4 does not seem to be present, delaying initialization.
    Jan 15 11:04:46 lppsq002a network[55905]: [FAILED]
    Jan 15 11:04:46 lppsq002a network[55905]: Bringing up interface eth5:  RTNETLINK answers: File exists
    Jan 15 11:04:46 lppsq002a network[55905]: [  OK  ]
    Jan 15 11:04:46 lppsq002a network[55905]: Bringing up interface eth6:  RTNETLINK answers: File exists
    Jan 15 11:04:47 lppsq002a network[55905]: [  OK  ]
    Jan 15 11:04:47 lppsq002a network[55905]: Bringing up interface eth7:  RTNETLINK answers: File exists
    Jan 15 11:04:47 lppsq002a network[55905]: [  OK  ]
    Jan 15 11:04:47 lppsq002a network[55905]: RTNETLINK answers: File exists
    Jan 15 11:04:47 lppsq002a network[55905]: RTNETLINK answers: File exists
    Jan 15 11:04:47 lppsq002a network[55905]: RTNETLINK answers: File exists
    Jan 15 11:04:47 lppsq002a network[55905]: RTNETLINK answers: File exists
    Jan 15 11:04:47 lppsq002a network[55905]: RTNETLINK answers: File exists
    Jan 15 11:04:47 lppsq002a network[55905]: RTNETLINK answers: File exists
    Jan 15 11:04:47 lppsq002a network[55905]: RTNETLINK answers: File exists
    Jan 15 11:04:47 lppsq002a network[55905]: RTNETLINK answers: File exists
    Jan 15 11:04:47 lppsq002a network[55905]: RTNETLINK answers: File exists
    Jan 15 11:04:47 lppsq002a systemd[1]: network.service: control process exited, code=exited status=1
    Jan 15 11:04:47 lppsq002a systemd[1]: Failed to start LSB: Bring up/down networking.
    Jan 15 11:04:47 lppsq002a systemd[1]: Unit network.service entered failed state.
    Jan 15 11:04:47 lppsq002a systemd[1]: network.service failed.
    Jan 15 11:08:22 lppsq002a systemd[1]: Starting LSB: Bring up/down networking…
    Jan 15 11:08:22 lppsq002a network[56841]: Bringing up loopback interface:  [  OK  ]
    Jan 15 11:08:22 lppsq002a network[56841]: Bringing up interface eth0:  RTNETLINK answers: File exists
    Jan 15 11:08:22 lppsq002a network[56841]: [  OK  ]
    Jan 15 11:08:26 lppsq002a network[56841]: Bringing up interface eth1:  RTNETLINK answers: File exists
    Jan 15 11:08:26 lppsq002a network[56841]: [  OK  ]
    Jan 15 11:08:26 lppsq002a network[56841]: Bringing up interface eth2:  ERROR     : [/etc/sysconfig/network-scripts/ifup-eth] Device eth2 has different MAC address than expected, ignoring.
    Jan 15 11:08:26 lppsq002a network[56841]: [FAILED]
    Jan 15 11:08:26 lppsq002a network[56841]: Bringing up interface eth3:  RTNETLINK answers: File exists
    Jan 15 11:08:27 lppsq002a network[56841]: [  OK  ]


2020-01-15-15_42_11-root-server

 

Another useful thing debug arguments is the -xe to do:

# journalctl -xe –no-pager

 

  • -x (– catalog)
    Augment log lines with explanation texts from the message catalog.
    This will add explanatory help texts to log messages in the output
    where this is available.
  •  -e ( –pager-end )  Immediately jump to the end of the journal inside the implied pager
      tool.

2020-01-15-15_42_32-root-server

Finally after fixing the /etc/sysconfig/networking-scripts/* IP configuration issues I had all the 8 Ethernet interfaces to work as expected
 

# systemctl status network


2020-01-15-16_15_38-root-server

 

 

2. Adding a new IP alias to eth0 interface


Further on I had  to add an IP Alias on the CenOS via its networking configuration, this is done by editing /etc/sysconfig/network-scripts/ifcfg* files.
To create an IP alias for first lan interface eth0, I've had to created a new file named ifcfg-eth0:0
 

linux:~# cd /etc/sysconfig/network-scripts/
linux:~# vim ifcfg-eth0:0


with below content

NAME="eth0:0"
ONBOOT="yes"
BOOTPROTO="none"
IPADDR="10.50.10.5"
NETMASK="255.255.255.0"


Adding this IP address network alias works across all RPM based distributions and should work also on Fedora and Open SuSE as well as Suse Enterprise Linux.
If you however prefer to use a text GUI and do it the CentOS server administration way you can use nmtui (Text User Interface for controlling NetworkManager). tool.
 

linux:~# nmtui

 

centos7_nmtui-ncurses-network-configuration-sysadmin-tool

nmtui_add_alias_interface-screenshot

Putty load as default session another session – Save other Putty session configuration to default howto

Thursday, November 29th, 2018

Reading Time: 2minutes

putty-load-button-screenshot

Recently I had to use PuTTY which I haven't used for years to open a number of SSH Pernanent Tunnels necessery for my daily work as a SAP Consultant.

I've saved them under a certain new profile and saved the set SSH Tunnel configuration not in the default Session but in separate named one, therefore had to press Load button every time after clicking over my Putty shortcut icon. 

That was annoying and took few seconds out of my life every next morning for about a week, so finally I found osme time to google it and it seemed it is pretty easy to have any Putty sessoin loaded you like.

Here is how:

1. Create a new Putty Shortcut

putty-screenshot1

putty-shortcut-screenshot-windows

Click over Putty icon while holding CTRL + SHIFT (Control SHIFT keys simultaneously ) and move the mouse somewhere on the desktop to create the shortcut.
 

2. Right click on Putty Shortcut

putty-target-screenshot-windows1

putty-target-screenshot-windows2

 

"C:\Program Files\PuTTY\putty.exe" -load "your_saved_session" "username@your_server_address" -pw "your_password"


fill out "target" field of shortcut using above code (alter to your own properties).
click Apply button.

If you need to pass a user and password from Shortcut itself (which is a bad practice for security but sometimes useful, for not so important Tunnels – for example a tunnel to an Open Proxy), do it by typing in the target field like so:
 

"C:\Program Files\PuTTY\putty.exe" -load "your_saved_session" "username@your_server_address" -pw "your_password"

 

And Hooray !!! After that when you click on PuTTy shortcut it loads your session automatically using given username and password.

Frogatto & Friends – One of the TOP 10 Arcade Free Software & Open Source Games for GNU / Linux and FreeBSD

Friday, December 16th, 2011

Reading Time: 4minutes
Frogatto old-school 2d jump and run free software game for GNU / Linux and FreeBSD
1. Frogatto & Friends – Is an Indian Free Software (Open Source) game in the spirit of old-school jump’en runs like Commander Keen, Prehistoric, Jazz Jack Rabbit

The game is really entertaining, the graphics looks approximately nice, the music is awesome, the gamelplay is good even though after some point in the game the moment with “where should I go now, I can’t find exit” comes through and it gets boring.

Generally if you compare with all the existing jump and run arcade games free software games available for Linux and FreeBSD the game will definetely arrange itself in the list of TOP 10 free software Arcade Games
and therefore its my own believe that Frogatto is a game that every GNU / Linux and FreeBSD desktop should have in Application -> Games GNOME menu.

Frogatto is rich of levels, enemies obstacles objects, places to visit (which puts it ahead of many of the linux arcade games which often miss enough game levels, has a too short game plots, or simply miss overall game diversity).

Frogatto linux freebsd game bombing airplaine

The game’s general look & feel is like a professional game and not just some tiny free software arcade, made by its authors for the sake to learn some programming, graphics or music creation.
Frogatto door leading to Grotto

Frogatto Free Software game wood screenshot

Besides that Frogatto & Friends is multi-platform supporting all the major operating systems.
Game supports:
 

  • Windows
  • Mac
  • iPhone
  • Debian GNU / Linux
  • FreeBSD

The game source code is also available on Frogatto.com – The Game’s Official website

The game is available as a deb package in Debian and Ubuntu GNU / Linuxes so to install on those deb based distributions, simply use apt:

debian:~# apt-get install frogatto
...

The above command will install two packages frogatto (containing the game’s main executable binary) and frogatto-data containinng all the game textures, levels, graphics, music etc.

BTW the package saparation on a gamename and gamename-data in Debian (for all those who have not still noticed), can be seen on most of the games with a game data that takes more disk space.

After the game is installed the only way to start the game is to run it manually through pressing ALT+F2 in GNOME or running the progrtam through gnome-terminal with cmd:

debian:~$ frogatto

Here are few more Frogatto gameplay screenshots:

Frogatto free open source game screenshot a game bad guy

Frogatto different level screenshot

I’ve noticed Frogatto is also available as an RPM package for Fedora Linux, as well as has a FreeBSD port in the /usr/ports/games/frogatto and this makes it easy to install on most free software OSes in the wild.

While checking frogatto.com , I found an interesting link to a website offering free graphics (pictures), textures and sounds for free and open source games for all those who hold interest into the development of Free Software & Open Source Games make sure you check OpenGameArt.org

OpenGameArt.org looks like a great initiative and will definitely be highly beneficial to the development of more and better FSOS Games so I wish them God speed with this noble initiative.

Frogatto is very suitable for growing kids since it doesn’t contain no violence and every now and then the main game actor the Frogatto Frog leads few lines English dialogues with some of the characters found in the quest.
For none speaking English countries, the game can help the kids to learn some basic english words and thus can help develop kids intellect and knowledge
And oh yeah one more criticism towards the game is the Enlish structure, it seems people who wrote the plot can work this out in the time to come. Many of the English sentences during dialogues the frog leads with the cranks he met does not sound like a common and sometimes even correct english / phrases.

Besides those little game “defect”, the game is pretty awesome and worthy to kill some time and relax from a long stressy day.

12 must have Joomla extension plugins / Essential modules for new Joomla CMS install

Thursday, June 16th, 2011

Reading Time: 10minutesJoomla bundle of must have extensions picture

These days very often I have to install, plain new Joomla based websites. I’ve realized that since there is no structured guide to follow describing the most essential plugins that every new fresh new joomla installation is required to have.
Thus I took the time and wrote this post, as it will be useful to myself in my future new joomla based websites establishment, I also believe these guide will be useful to other Joomla enthusiasts or administrators in their daily work.

Below I will describe in short the installation, configuration and oddities I’ve faced during installment of the above described bundle of plugins on a plan Joomla 1.5 install.These article will walk through 12 joomla essential plugins that I believe every fresh Joomla installation should be equipped with.
Hope this guide will be helpful to you. Now let’s start it up:

1. JoomlaXplorer – A sophisticated web file explorer for Joomla

One of the basic modules, beneficial with a new joomla CMS install is Joomla Xptplorer . This module enables the joomla admin to browse files in a web file explorer, on the server where the joomla CMS is installed. Below you see how handy the joomla web explorer provided by the plugin is:

Joomla file explorer extplorer module

Installing and using the plugin is a piece of cake. To install the plugin:

a. download Joomla file Xplorer from here or from the official plugin website.

b. Install the plugin through the admin joomla menu:

Extensions -> Install/Uninstall

c. Start using the newly installed plugin by following to menus:

Components -> eXtplorer

2. JCrawler Generate easily sitemap.xml to aim the overall Joomla website SEO optimization

JCrawler logo plugin joomla

I have previously written a very through tutorial on how to install configure and generate website sitemap with Jcrawler module, You can read my article titled: How to build website sitemap.xml in Joomla here

3. sh404SEF – Make your Joomla links and content more user friendly

sh404sef Joomla Search Engine Optimization plugin

sh404SEF is a great Joomla plugin, which will seriously improve SEO and could contribute well for a website to be better indexed with major search engines.

I have previously written an article describing thoroughfully the install and use procedures for the module.
You can read the article Making your Joomla URLS Google friendly with sh404sef plugin / Simple Joomla link SEO here

4. Akeeba Backup Joomla solution

Akeeba backup Joomla Module

Installing a joomla backup solution is very essential if you does take care about your data, it often happens that server hard disk got crashes or a RAID massives got corrupted or some kind of other unexpected disaster hits the server. In these terrible times, having a website backup will save you nerves and data recovery funds, not to mention that in many cases data recovery is impossible.

Joomla has a very easy to use software for creating full website backup called Akeeba Backup

To start using the software one must:

a.Download Akeeba Backup and install it via:

Extensions -> Install/Uninstall

After the Akeeba Backup installation is over, to create your first backup, one needs to navigate to:

Components -> Akeeba Backup -> Backup Now

Each Akeeba backup (a version of the website’s files data and sql info) will be created in an archive file with the extension .jpa
The backup files are created under joomla’s website (main) root directory in directory location administrator/components/com_akeeba/backup

The Akeeba plugin also has capabilities to recover a (.jpa) backup restore point easily.
To recover a backup with the Akeeba plugin one needs to do it once again, via the plugin joomla web interface.
5. Google Analytics (place easy tracking code) in Joomla

Google Analytics Tracking Module for Joomla

a. Download the Google Analytics Tracking Module
The module is available from Joomla Extensions on joomla.org

At the current time of writting you need to download the analytics_tracking15,zip file

b. Install the Google Analytics Tracking Module;
Login as joomla admin and navigate to;

Extensions -> Install

Place the analytics_tracking15.zip url to the Install URL: field.
Again as of time of writting you need to place https://pc-freak.net/files/analytics_tracking15.zip;

c. Open the Module Manager

Extensions -> Module Manager

d. Click over Google Analytics Tracking Module
On the right pane you will notice in the Module Parameters the Analytics_uacct_code field. In the uacct_code field you need to paste your UA obtained from your created google-analytics account.
This code is usually something like UA-2101595-10
Now place your code their and press the save green button located near the right top of the screen. You should see the text in blue Item Saved which would indicate your UA code is stored already in the Google Analytics Tracking Module, now press the Cancel button located again on the right top.
As a last step before the Google analytics is set-up on the Joomla you need to enable the plugin to do you need to press over the tick left sided from the text reading Google Analytics Tracking Module in the Module Manager
e. Click over the Enabled button in Module Manager;
Google Analytics Tracking Module -> Enabled

6. Itprism (Facebook, Twitter etc.) Social Network share buttons Joomla plugin

ITPShare Large Social Buttons Joomla

a. to add the itpsocialbuttons to joomla Download the Itpsocialbuttons latest module files from http://itprism.com/free-joomla-extensions/social-buttons-plugin or use my mirrored module files below:

Download mod_itpsocialbuttons .zip file
Download plg_itpsocialbuttons .zip

After having the two files necessery to be installed to make the ITPSocialButtons appear on website, installation is done like with any other installation:

Extensions -> Install/Uninstall -> Upload Package File (Choose File)

Next its necessery to configure the plugin to do so, follow to menus:

Extensions -> Module Manager -> Share

You will notice the Share dialog in the list of Module Name column in Module Manager

Here is a screenshot on how the settings options for ITpsocialbuttons will look like:

Mod ITpSocialButtons settings screen

The options which I personally changed was:

Show Title – I set this one to No as I wanted to omit the plugin title text to appear on my website.
Further on I’ve set the Enabled option to Yes to enable the plugin and choose the buttons Style option to be of a Small buttons type.
I’ve also found that the most suitable position for the Social Share buttons were to be of a right – Position .

Here is how the social network itprism share buttons looks like:

ITprism Joomla Social Share Plugin various button types

The plugin supports sharing of joomla pages to the following list of social networks:
 

  • Delicios.com
  • Digg.com
  • Facebook
  • Google Bookmarks
  • StumbleUpon
  • Technorati
  • Twitter
  • LinkedIn

The module configuration, also allows the user to configure the type of social network buttons, one wants to display on the website.

7. Joomla JCE Content Editor

This content editor is really awesome compared to the default editor TinyMCE. If you want to have an options rich content editor for Joomla, then this is the one for you 🙂
download JCE Content Editor here

After installing the JCE Joomla content editor in order to enable it as a default editor you need to go to the following location:

Site -> Global Configuration -> Default WYSIWYG Editor

There place on Editor TinyMCE and change it with Editor – JCE

Now go to edit some article, and you will see the difference in the editor 🙂

8. Add gallery Joomla capabilities with sigplus (Image Gallery Plus) and Very Simple Image Gallery

Image Gallery Plus sigplus Joomla Screenshot

Image Gallery Plus plugin (sigplus) gallery review screenshot

sigplus Image Gallery Plus is a straightforward way to add image or photo galleries to a Joomla article with a simple syntax. It takes a matter of minutes to set up a gallery but those who are looking for a powerful gallery solution will not be disappointed either: sigplus is suitable for both beginner and advanced users.

Download Sigplus Joomla Image Gallery plugin here
Using sigllus is quite easy all one has to do is use Joomla Media Manager from links:

Site -> Media Manager

Create new folder in the stories folder, let’s say New Pictures and further on use Media Manager to upload all desired pictures to be later displayed.

Being done with uploading the images you want to display, go to Article Manager :

Content -> Article Manager

From there choose your article where new uploaded pictures you want to display and type in the article:

{gallery}New Pictures{/gallery}.

Note that New Pictures is the directory just recently created as stated below, it’s important that there is no spacing between {gallery}and New Pictures, if one tries {gallery} New Pictures {/gallery} instead of {gallery}New Pictures{/gallery} an error will occur instead of the pictures being displayed in a scrolled gallery.

Sigplus Image Gallery has also a number of configuration options, which might make it look a bit more decent.
I have to say in my view the default way sigplus displays pictures is awful!

Another alternative if you don’t like Sigplus ‘s way of creating new galleries is to use Very Simple Image Gallery

Very Simple Image Gallery joomla screenshot

Here is a screenshot on a sample gallery created with Very Simple Image Gallery Joomla Plugin

You can download Very simple image gallery here

After installing the plugin. It’s use is analogous to the Sigplus . To use it likewise sigplus create new directory through Media Manager and in stories and upload your files in let’s say New Pictures1 . Later on in your article place, the code

{vsig}New Pictures1{/vsig}

Gallery will be generated automatically by the plugin. I think Simple Image Gallery is a bit more advanced and gives a better outlook to Galleries, though it’s configuration settings are much less than with SigPlus image gallery.

To add pictures comments e.g. img link alt=” and title=” tib you need to place a code within the Article manager similar to:

{vsig_c}0|Picture_1.JPG|Some sample text|Some other text{/vsig_c}
{vsig_c}0|Picture_2.JPG|Some example text|Some text{/vsig_c}
etc. ..

Note that the 0 in above example specifies the gallery number if you for instance are using a couple of galleries with Simple Image Gallery , the first one you used would be call 0 . The text specified as comments to the picture will also appear after you preview the gallery right below the picture when clicked on as a picture description in a really nice way.
9. Install Google maps plugin for Joomla

Google Maps plugin for Joomla screenshot

It’s a wise idea that every website has a location map on it’s website, for that reason Google maps is just great.
To install Google maps capability to joomla one can use a plugin called Google Maps .

You can straighly download Joomla’s Googlemap plugin from here

Afterwards use Extension Manager to install the plugin e.g. follow:

Extensions -&gr; Install/Uninstall (Choose File)

and click on Upload File & Install button.

To further enable and configure the Joomla Googlemap plugin you will have to go to the location:

Extensions -> Plugin Manager

Therein you will have to find and enable the Google Maps plugin which is to be found in the column named Plugin Manager
On my Joomla installation the plugin was located in the second page with modules, so if you don’t find the module on the listing with modules on the first page, make sure you scroll to the bottom of the page and click on Next button.

Therein in the list you will most likely notice Google Maps use the Enable button to enable it.

Next step is to configure the plugin, to do so press on the plugin name Google Maps
All configuration necessery here is to place Googlemaps API Key in the respective field (you will see it among config options).

Issuing a new Google Maps api key takes just few seconds, if you already have a gmail account just go to http://code.google.com/apis/maps/signup.html and take few seconds to issue the key.

You will get the key right on your gmail account after being issued (to repeat myself issuing takes few seconds so no worrier here).

One moreOnce having the key place it in the Googlemaps API Key field and configuring Address (which is one of the list of many options the plugin provides) you will be done with configuration.

To display a google map the location you just configured go to the Article Manager , select the article where you want the google maps location picture of your address to appear and type in the Article:

{mosmap|text='Exact street address location'|zoom='15'|zoomType='Large'|zoomNew='0'}

After you save the article a very nice Google map showing you the location’s streets will appear.
You can further conifgure a number of things related to the google map to appear, one thing you might want to play with is the zoom option which as you see in below’s code is equal to 15, e.g. zoom=’15’
Set it to another one if you want to regulate your googlemaps zoom level. For more thoroughful options take a look at the extensive plugin documentation.

10. Joomla Xmap (generating static HTML sitemap)Download Xmap from here , install it the usual plugin way.

Right after installation on the plugin succesful install screen you will notice the link component menu .
Clicking on the component menu you will be leaded to a page showing you few links Sitemap’s URL :
 

  • XML Sitemap:
  • HTML Sitemap:
  • News Sitemap:
  • Images Sitemap:

11. Add Joomla donate Paypal capabilities with Joomla PAYPAL DONATION MODULE

Paypal Donation Module Joomla Screenshot

Just recently I’ve written a a post on how to add a paypal donation capabilities to joomla, you can read my previous post here

12. Install Joomla RSForms Module (Advanced Joomla Forms Support)

Simple Joomla RsForm contact form

If you’re planning to add a complicated form support for Joomla, there are plenty of plugins, however one that was suggested by a friend of mine which is deep in Joomla world and moreover works good on my joomla installations is RSForms

Joomla – RSForms! is free to download and has great and easy interface to create new joomla forms.

At the time of writting I use these three RSForms components on new Joomla installations:

RSform Pro 1.1.0 com
Mod RsForm for Joomla 1.5
Mod Rsform list for Joomla

For latest release of RSForms! use the link http://www.rsjoomla.com/joomla-components/rsform.html

Installation is like any other module and is done through Extensions -> Install/Uninstall menu.

After installation, setting up a new form is available from the Joomla Menus:

Components -> RSform!Pro -> Manage Forms

I would not enter in details on how to edit the default RSForms or create a new RSForm. Just take some time and learn it by trying 😉

After the rsform is ready, to enable the new form, navigate to Joomla menus:

Menus -> Main Menu

Press the New button located in the buttons bar nearby the page header in the list of options in Select Menu item Type you will notice the RSForm!Pro as an option, press on it to establish the new form in the menus.

A follow up window will appear where one can set a Title: and Alias: for the new form as well as few other options.
After finalizing the settings press on Apply button to save the settings and the new form should appear in Joomla.

Probably there are many more handy plugins, which I’m missing here thus I’ll be glad if readers suggest some more helpful essential (must have plugins) for Joomla.
Feedback on this tutorial is very welcome!
Looking forward to hear for your opinions if my article was helpful to you 😉

How to Turn Off, Suppress PHP Notices and Warnings – PHP error handling levels via php.ini and PHP source code

Friday, April 25th, 2014

Reading Time: 2minutes

php-logo-disable-warnings-and-notices-in-php-through-htaccess-php-ini-and-php-code

PHP Notices are common to occur after PHP version upgrades or where an obsolete PHP code is moved from Old version PHP to new version. This is common error in web software using Frameworks which have been abandoned by developers.

Having PHP Notices to appear on a webpage is pretty ugly and give a lot of information which might be used by malicious crackers to try to break your site thus it is always a good idea to disable PHP Notices. There are plenty of ways to disable PHP Notices

The easiest way to disable it is globally in all Webserver PHP library via php.ini (/etc/php.ini) open it and make sure display_errors is disabled:

display_errors = 0

or

display_errors = Off

Note that that some claim in PHP 5.3 setting display_errors to Off will not work as expected. Anyways to make sure where your loaded PHP Version display_errors is ON or OFF use phpinfo();

It is also possible to disable PHP Notices and error reporting straight from PHP code you need code like:

 

<?php
// Turn off all error reporting
error_reporting(0);
?>

 

or through code:

 

ini_set('display_errors',0);


PHP has different levels of error reporting, here is complete list of possible error handling variables:

 

 

 

<?php
// Report simple running errors

error_reporting(E_ERROR | E_WARNING | E_PARSE);

// Reporting E_NOTICE can be good too (to report uninitialized
// variables or catch variable name misspellings …)

error_reporting(E_ERROR | E_WARNING | E_PARSE | E_NOTICE);

// Report all errors except E_NOTICE
// This is the default value set in php.ini

error_reporting(E_ALL ^ E_NOTICE);
// Report all PHP errors (see changelog)

error_reporting(E_ALL);
// Report all PHP errors error_reporting(-1);
// Same as error_reporting(E_ALL);

ini_set('error_reporting', E_ALL); ?>

The level of logging could be tuned on Debian Linux via /etc/php5/apache2/php.ini or if necessary to set PHP log level in PHP CLI through/etc/php5/cli/php.ini with:

error_reporting = E_ALL & ~E_NOTICE

 

If you need to remove to remove exact warning or notices from PHP without changing the way  PHPLib behaves is to set @ infront of variable or function that is causing NOTICES or WARNING:
For example:
 

@yourFunctionHere();
@var = …;


Its also possible toDisable PHP Notices and Warningsusing .htaccess file (useful in shared hosting where you don't have access to global php.ini), here is how:

# PHP error handling for development servers
php_flag display_startup_errors off
php_flag display_errors off
php_flag html_errors off
php_flag log_errors on
php_flag ignore_repeated_errors off
php_flag ignore_repeated_source off
php_flag report_memleaks on
php_flag track_errors on
php_value docref_root 0
php_value docref_ext 0
php_value error_log /home/path/public_html/domain/php_errors.log
php_value error_reporting -1
php_value log_errors_max_len 0

This way though PHP Notices and Warnings will be suppressed errors will get logged into php_error.log

How to detect failing storage LUN on Linux – multipath

Wednesday, April 16th, 2014

Reading Time: 2minutes

detect-failing-lun-on-linux-failing-scsi-detection

If you login to server and after running dmesg – show kernel log command you get tons of messages like:

# dmesg

 

end_request: I/O error, dev sdc, sector 0
sd 0:0:0:1: SCSI error: return code = 0x00010000
end_request: I/O error, dev sdb, sector 0
sd 0:0:0:0: SCSI error: return code = 0x00010000
end_request: I/O error, dev sda, sector 0
sd 0:0:0:2: SCSI error: return code = 0x00010000
end_request: I/O error, dev sdc, sector 0
sd 0:0:0:1: SCSI error: return code = 0x00010000
end_request: I/O error, dev sdb, sector 0
sd 0:0:0:0: SCSI error: return code = 0x00010000
end_request: I/O error, dev sda, sector 0
sd 0:0:0:2: SCSI error: return code = 0x00010000
end_request: I/O error, dev sdc, sector 0
sd 0:0:0:1: SCSI error: return code = 0x00010000
end_request: I/O error, dev sdb, sector 0
sd 0:0:0:0: SCSI error: return code = 0x00010000
end_request: I/O error, dev sda, sector 0

 

In /var/log/messages there are also log messages present like:

# cat /var/log/messages
...

 

Apr 13 09:45:49 sl02785 kernel: end_request: I/O error, dev sda, sector 0
Apr 13 09:45:49 sl02785 kernel: klogd 1.4.1, ———- state change ———-
Apr 13 09:45:50 sl02785 kernel: sd 0:0:0:1: SCSI error: return code = 0x00010000
Apr 13 09:45:50 sl02785 kernel: end_request: I/O error, dev sdb, sector 0
Apr 13 09:45:55 sl02785 kernel: sd 0:0:0:2: SCSI error: return code = 0x00010000
Apr 13 09:45:55 sl02785 kernel: end_request: I/O error, dev sdc, sector 0

 

 

This is a sure sign something is wrong with SCSI hard drives or SCSI controller, to further debug the situation you can use the multipath command, i.e.:


multipath -ll | grep -i failed
_ 0:0:0:2 sdc 8:32 [failed][faulty]
_ 0:0:0:1 sdb 8:16 [failed][faulty]
_ 0:0:0:0 sda 8:0 [failed][faulty]

 

As you can see all 3 drives merged (sdc, sdb and sda) to show up on 1 physical drive via the remote network connectedLUN to the server is showing as faulty. This is a clear sign something is either wrong with 3 hard drive members of LUN – (Logical Unit Number) (which is less probable)  or most likely there is problem with the LUN network  SCSI controller. It is common error that LUN SCSI controller optics cable gets dirty and needs a physical clean up to solve it.

In case you don't know what is storage LUN? – In computer storage, a logical unit number, or LUN, is a number used to identify a logical unit, which is a device addressed by the SCSI protocol or protocols which encapsulate SCSI, such as Fibre Channel or iSCSI. A LUN may be used with any device which supports read/write operations, such as a tape drive, but is most often used to refer to a logical disk as created on a SAN. Though not technically correct, the term "LUN" is often also used to refer to the logical disk itself.

What LUN's does is very similar to Linux's Software LVM (Logical Volume Manager).

Make Viber calls with no smartphone from Mobile to PC and from PC to Mobile – Bluestacks install android mobile apps on PC

Thursday, April 24th, 2014

Reading Time: 5minutes

Viber-for-smartphones-connect-freely-through-internet-voip-on-your-mobile

Since I've bought ZTE smat phone and I have Android on it, decided to install   Viber – iOS, Android and Desktop PC – Free Calls, Text and Picture sharing through the internet app. Viber is used by a lot of my people including many friends already so I installed it as well to be possible to speak for free with close friends …

Why Viber?


What makes this nifty app so great is its capability to makefree calls over mobile phones through the InternetViber.
Viber saves you a lot of money as calls are handled only through the Internet (you need Wifi on your mobile or Mobile 3G Internet access on phone) and you don't need to pay to your mobile operator 0.10 – 0.15 euro / cents per minute. Besides being Free another advantage of Viber is conversations sound quality which is much better than a regular phone call

Viber doesn't need a special registration, but as (login) identificator uses your mobile phone number – you just need to have a working Mobile operator phone num. Once registered under a number even if you change your mobile sim card to other operator (for example moving from country to country) still the Viber account will continue work. Another good reason to use Viber is it makes possible price free calls between different countries (for example if you travel a lot and you want to regularly speak with your wife) – in my case right now I'm in Bulgaria and my wife is in Belarus, so to save money and keep talking daily we use Viber daily.

What Devices and Operating System Viber Supports and what is Viber advantages / disadvantages ?


Another reason why Viber is so great is its multi-platform support it works on iPhone, Blackberry, Windows Phone, Nokia (Symbian), Windows, Mac OS and even (Korean own OS-ed) Bada devices. Some might argue that Viber is inferior to Skype and interms of Voice and Video quality its better because of its enhanced HD voice enhanced codecs, besides that Viber's video is still in Beta. However Viber has one big advantage it makes easy possible to reach people using just their Mobile Phone numbers where in Skype it takes time and effort to register in Skype install application on your Mobile keep yourself logged in in Skype and have all contacts previously added, all this happens automatically in Viber in time of installation of Viber App on your mobile.
 

Which Is Cheaper Viber or Skype?

Skype_VS_Viber-VOIP-Prices-which-is-cheaper-skype-or-viber


Once installed Viber could integrate itself with rest of your Mobile OS Call Manager and in time of call a friend number you have the opportunity to make it free Viber call. Viber are also selling Viber Credits so if you want to use your Viber Voice Over IP you can call external mobile operator numbers on a very very cheap price. Viber Calls to landline or mobile phones could be up to 400% cheaper than Skype! Whether you own a Smartphone it will be nice to give Viber a try.

Viber – How to make Phone calls between Desktop PC and Smarphone Mobile

 

One not so standard Viber use is to make Viber calls with no smartphone (at hand) from PC to another Viber equipped Mobile and vice versa.
I needed to make Viber calls from my ZTE Android running mobile to my wife's MacBook Air PC because her mobile is an old Nokia running obscure Symbian version which is not supporting Viber + she doesn't have an Internet access tariff switched on her mobile.

Here is what I had to do to make Phone calls between my Mobile Viber App and my wife's MacbookAir Notebook PC:
 

  • Install BlueStacks Web App Player

     

     

     

    BlueStacks_emulate-google-appstore-on-Windows-and-Mac-OS-android-emulator_Logo
    BlueStacks App Player is a software designed to enable Android applications to run on Windows PC, Apple Macintosh Computers and Windows tablets. BlueStacks is something like (VMware, Qemu) Virtual Machine which allows you to install and run any Android App on your Desktop PC.
    Its curious that app was created by Rosen Sharma in 2008 an ex CTO (Chief Technology Officer) of McAfee
     

  •  A mobile phone with a working SIM card (Nokia 6310 or any old mobile no need to be a smartphone
     
  • Desktop PC with Windows 7, 8 or PC with Mac OS


Install Bluestacks

BlueStacks is needed in order to emulate a smartphone on your PC, therefore once setupped Bluestacks. Launch it and  inside its necessary to login with your Gmail (Google Account) in order to allow access to Google Play Appstore on your PC.
viber with no mobile phone bluestacks
 

Installing and Verifying Viber

This is the most crucial and tricky part in order to make Viber working on any device you need to receive a special Viber verification code, you need to fill in this code to confirm Viber installation on PC. Here I assume you have BlueStacks running with Viber Application installed.

viber-running-under-bluestacks-on-windows-7-8-screenshot

First will be prompted to Agree with Terms and Conditions and provide Mobile Phone number for verification. Tell the Viber app that you have a smartphone with Viber already when prompted. After receving Viber Verification Code you need to fill in this code into BlueStacks Window (inside Viber should be running), go further to next step and you should be done with Desktop PC Viber number registration.

N.B. ! One brackets to open here is you need to have a working Mobile Phone number where you will receive the verification code as SMS, otherwise you cannot get the verification. On your filled in mobile phone number you will get the verification code as SMS.

Making Viber Calls to (Windows Mac) PC without Smartphone

There is no more further need for BlueStacks so you can uninstall it, however I preferred to keep it as its useful to be able to install Android Applications straight on your Desktop PC. To start using Viber on Desktop, just launch Viber application (not through BlueStacks) but the direct install.

Use Viber dial pad to dial your desired remote Smartphone number with Viber equipped.
Enjoy the free Internet calls ! 🙂
 

find text strings recursively in Linux and UNIX – find grep in sub-directories command examples

Tuesday, May 13th, 2014

Reading Time: 2minutes

unix_Linux_recursive_file_search_string_grep
GNU Grep
is equipped with a special option "-r" to grep recursively. Looking for string in a file in a sub-directories tree with the -r option is a piece of cake. You just do:

grep -r 'string' /directory/

or if you want to search recursively non-case sensitive for text

grep -ri 'string' .
 

Another classic GNU grep use (I use almost daily) is whether you want to match all files containing (case insensitive) string  among all files:

grep -rli 'string' directory-name
 

Now if you want to grep whether a string is contained in a file or group of files in directory recursively on some other UNIX like HP-UX or Sun OS / Solaris where there is no GNU grep installed by default here is how to it:

find /directory -exec grep 'searched string' {} dev/null ;

Note that this approach to look for files containing string on UNIX is very slowThus on not too archaic UNIX systems for some better search performance it is better to use xargs;

find . | xargs grep searched-string


A small note to open here is by using xargs there might be weird results when run on filesystems with filenames starting with "-".

Thus comes the classical (ultimate) way to grep for files containing string with find + grep, e.g.

find / -exec grep grepped-string {} dev/null ;

Another way to search a string recursively in files is by using UNIX OS '*' (star) expression:

grep pattern * */* */*/* 2>/dev/null

Talking about recursive directory text search in UNIX, should mention  another good GNU GREP alternative ACK – check it on betterthangrep.com 🙂 . Ack is perfect for programmers who have to dig through large directory trees of code for certain variables, functions, objects etc.

 

Shutdown tomcat server node in case of memory depletion – Avoiding Tomcat Out of memory

Friday, June 6th, 2014

Reading Time: 2minutes

fix-avoid-tomcat-out-of-memory-logo

Out Of Memory Errors, or OOMEs, are one of the most common problems faced by Apache Tomcat users. Tomcat cluster behind Apache unreachable (causing customer downtimes). OOME errors occur on production servers that are experiencing an unusually high spike of traffic.

Out of memory errors are usually a problem of application and not of Tomcat server. OMEs have become such a persistent topic of discussion in the Apache Tomcat community cause its so difficult to trace to their root cause. Usually 'incorrect' web app code causing Tomcat to run out of memory is usually technically correct.

Most common reasons for Out of Memory errors in application code are:
 

  •     the heap size being too small
  •     running out of file descriptors
  •     more open threads than the host OS allows
  •     code with high amounts of recursion
  •     code that loads a very large file into memory
  •     code that retaining references to objects or classloaders
  •     a large number of web apps and a small PermGen


The following java option -XX:OnOutOfMemoryError= could be added to any of tomcat java application servers in setenv.sh in  JAVA_OPTS= variable in case of regular Out of Memory errorsoccur making an application unstable.

-XX:OnOutOfMemoryError=<path_to_tomcat_shutdown_script.sh>

Where < path_to tomcat_shutdown_script.sh > is shutdown script(which performs kill <tomcat_pid> if normal shutdown fails) for the tomcat instance.

With this setup if any tomcat instance run out of memory it will be shutdown (shutdown script invoked) – as result the Apache proxy infront of Tomcats should not pass any further requests to this instance and application will visualize / work properly for end customers.

Usually a tomcat_shutdown_script.sh to invoke in case of OOM would initiate a Tomcat server restart something like:

for i in `ps -ef |grep tomcat |grep /my_path_to_my_instance | awk '{print $2}'`
do
kill -9 "$i"
#path and script to start tomcat
done

To prevent blank pages returned to customer because of shutdown_script.sh starting stopping Tomcat you can set in Reverse Apache Proxy something like:
 

<Proxy balancer://mycluster>
   BalancerMember ajp://10.16.166.48:11010/ route=delivery1 timeout=30 retry=1
   BalancerMember ajp://10.16.166.70:11010/ route=delivery2 timeout=30 retry=1
</Proxy>

Where in above example I assume, there are only two tomcat nodes, for more just add respective ones.

Note that if the deployed application along all servers is having some code making it crash all tomcat nodes can get shutdown all time and you can get in a client havoc 🙂