linux commands for every web developer/Software engineer

scp - Linux command line tool to copy files over ssh

scp [[user@]from-host:]source-file [[user@]to-host:][destination-file]

scp  abc.TXT root@10.215.3.150:/home/user/xyz.TXT

from-host

Is the name or IP of the host where the source file is, this can be omitted if the from-host is the host where you are actually issuing the command

user

Is the user which have the right to access the file and directory that is supposed to be copied in the cas of the from-host and the user who has the rights to write in the to-host

source-file

Is the file or files that are going to be copied to the destination host, it can be a directory but in that case you need to specify the -r option to copy the contents of the directory

destination-file

Is the name that the copied file is going to take in the to-host, if none is given all copied files are going to maintain its names

Copy Multiple fies

scp root@192.168.168.052:/home/ftp-124/5656/$dir/\{abc.txt,def.txt,ghi.txt\} root@192.168.168.053:/home/shahzeb

Restart MySql Ubuntu

To restart Apache2 on Ubuntu, we enter the following command in a terminal such as bash:

restart mysql

service mysql start

Restart Apache2 Ubuntu

To restart Apache2 on Ubuntu, we enter the following command in a terminal such as bash:

/etc/init.d/apache2 restart

Of course, you most likely will need to be the superuser to do that so you might need to enter the following command and then your password when requested:

sudo /etc/init.d/apache2 restart

Pointer

use pointer to acees the variable within a variable directly like

 foo=bar
 name=foo
 echo ${!name}
Result : bar

grep command: 

grep command usually interpet "|" as "AND" sign but you can use the same "|" for "OR" sign

for example

zgrep "^2012-06-05" /var/path/to/file/abc12346-12-06* | grep -E '3003300356|3003301763|3008203898|3008202542|3008226266|3003404159'

zgrep = grep for gzipped files

some of the basic linux command

There are many common Linux commands that will be helpful to you, if you ever even use the command line interface in Linux. Most average users just use the graphical user interface instead which usually has many tools and front-ends to Linux common commands. This Linux tutorial on command commands will help even the average user in case X server crashes, fails, is not properly configured, etc. So continue reading for some of the more common Linux bash commands.

Some of the more common Linux shell commands are listed below for more information on each command you can always run man [command] and this will bring up the manpage for that command, you can also click on the commands listed for some common examples and syntax.
First before I list them any syntax in [] will need some kind of input from you normally, for example:
man [command] you will want to actually replace [command] with the shell command you want to read the man page for: man ls will give you the man page for the Linux shell command ls.

• linux ls command – is used to list files on the filesystem.
• file – command that will check the filetype, this will output to you what the file type is no matter what the extension is.
• mkdir command – used to make directories on the filesystem.
• cd – is used for changing into a different directory in the Linux shell
• cp – is the Linux copy command, this shell command is used to copy files|directories from one location on the filesystem to another.
• mv – the Linux terminal command to move files|directories. Like the cp command, but deletes the original source.
• rm – shell command in Linux to remove files|directories.
• Linux cat command- this command is used to print|view the contents of a file to the screen|terminal.
• grep – command used to search|find contents of a file and print|view on your terminal|screen.
• Linux more and less – commands that will allow you to read output of files, unlike cat that will output the entire file at once, even if it is too large for your terminal more and less will output only as many lines as the shell you are in can output, and allow you to scroll through the file contents.
• chown – Linux command to change ownership of a file|directory.
• Linux chmod – command that allows you to change mode of user access|permissions, basically set read, write, and execute permissions.
• Linux ps – lists the current running processes on your Linux system
• Linux kill and killall commands – used to kill|terminate running processes

Unpacking or uncompressing gz files under Linux and UNIX systems

Using gunzip command:

$ gunzip file.gz
$ ls file

Using gzip -d command:

$ gzip -d file.gz
$ ls file

If file extension is tar.gz, type the command:

$ tar -zxvf file.tar.gz

Please note that gunzip can currently decompress files created by gzip, zip, compress, compress -H or pack programs.

Chromium on Ubuntu ! [HOW TO]

Chromium is an open source web browser. The project was founded by Google, which built Google Chrome on top of the code of Chromium. Sadly enough, only a Windows version of Google Chrome as been released, leaving the rest of us in the dust.
What I learned today is pretty awesome.
While I knew that Linux and Mac versions were in the works, I found out that a PPA repository for daily builds of Linux’s Chromium does exist ! (we’re talking about a native non-using Wine version)
Before explaing how to install it, let me just specify we’re talking about alpha builds, and pretty incomplete ones. Just basic web surfing works.: Chromium may don’t work, make your loose data or make your loose your cat. Remember if that anything breaks, you’re on your own – install it only if you’re confortable with restoring your system/data. Also keep in mind this disclaimer on the PPA’s launchpad page:
Ubuntu daily builds of the Chromium browser.
The PPA is maintained by a bot, so it contains completely untested builds, mostly useful to track regressions or if you are curious, or just brave.
The package is still a work-in-progress, so is Chromium, please be patient.
FAQ: no native 64bit debs planed for now. The amd64 package is using ia32-libs.
Project page for Chromium in Ubuntu: https://launchpad.net/chromium-project
How to install Chromium on Ubuntu

Open your /etc/apt/sources.list file !
gksudo gedit /etc/apt/sources.list

Add these lines at the very bottom of it:

deb http://ppa.launchpad.net/chromium-daily/ppa/ubuntu intrepid main
deb-src http://ppa.launchpad.net/chromium-daily/ppa/ubuntu intrepid main

then upload and install:

sudo apt-get update
sudo apt-get install chromium-browser

Update: due to some bug Chromium requires the msttcorefonts package to actually show content (otherwise it will just show a blank content area). So, make sure to have multiverse repositories enabled and also type:

sudo apt-get install msttcorefonts

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Installing Apache2 With PHP5 And MySQL On Ubuntu 10.10 (LAMP)

LAMP is short for Linux, Apache, MySQL, PHP. This tutorial shows how you can install an Apache2 webserver on an Ubuntu 10.10 server with PHP5 support (mod_php) and MySQL support.

1 Preliminary Note

In this tutorial I use the hostname server1.example.com with the IP address 192.168.0.100. These settings might differ for you, so you have to replace them where appropriate.I'm running all the steps in this tutorial with root privileges, so make sure you're logged in as root:

sudo su

2 Installing MySQL 5

First we install MySQL 5 like this:

aptitude install mysql-server mysql-client

You will be asked to provide a password for the MySQL root user - this password is valid for the user root@localhost as well as root@server1.example.com, so we don't have to specify a MySQL root password manually later on:

New password for the MySQL "root" user: <-- yourrootsqlpassword
Repeat password for the MySQL "root" user: <-- yourrootsqlpassword

3 Installing Apache2

Apache2 is available as an Ubuntu package, therefore we can install it like this:

aptitude install apache2

Now direct your browser to http://192.168.0.100, and you should see the Apache2 placeholder page (It works!):
Apache's default document root is /var/www on Ubuntu, and the configuration file is /etc/apache2/apache2.conf. Additional configurations are stored in subdirectories of the /etc/apache2 directory such as /etc/apache2/mods-enabled (for Apache modules), /etc/apache2/sites-enabled (for virtual hosts), and /etc/apache2/conf.d.

4 Installing PHP5

We can install PHP5 and the Apache PHP5 module as follows:

aptitude install php5 libapache2-mod-php5

We must restart Apache afterwards:

/etc/init.d/apache2 restart

5 Testing PHP5 / Getting Details About Your PHP5 Installation

The document root of the default web site is /var/www. We will now create a small PHP file (info.php) in that directory and call it in a browser. The file will display lots of useful details about our PHP installation, such as the installed PHP version.

vi /var/www/info.php
<?php phpinfo(); ?>

Now we call that file in a browser (e.g. http://192.168.0.100/info.php):
As you see, PHP5 is working, and it's working through the Apache 2.0 Handler, as shown in the Server API line. If you scroll further down, you will see all modules that are already enabled in PHP5. MySQL is not listed there which means we don't have MySQL support in PHP5 yet.

6 Getting MySQL Support In PHP5

To get MySQL support in PHP, we can install the php5-mysql package. It's a good idea to install some other PHP5 modules as well as you might need them for your applications. You can search for available PHP5 modules like this:

aptitude search php5

Pick the ones you need and install them like this:

aptitude install php5-mysql php5-curl php5-gd php5-idn php-pear php5-imagick php5-imap php5-mcrypt php5-memcache php5-mhash php5-ming php5-ps php5-pspell php5-recode php5-snmp php5-sqlite php5-tidy php5-xmlrpc php5-xsl php5-json

Now restart Apache2:

/etc/init.d/apache2 restart

Now reload http://192.168.0.100/info.php in your browser and scroll down to the modules section again. You should now find lots of new modules there, including the MySQL module:

7 phpMyAdmin

phpMyAdmin is a web interface through which you can manage your MySQL databases. It's a good idea to install it:

aptitude install phpmyadmin

You will see the following questions:
Web server to reconfigure automatically: <-- apache2
Configure database for phpmyadmin with dbconfig-common? <-- No
Afterwards, you can access phpMyAdmin under http://192.168.0.100/phpmyadmin/:

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* Acts as an inexpensive showroom, storefront and salesperson to your local market and beyond — 24 hours a day, seven days a week.
* Serves to satisfy the phenomenon of customers increasingly researching purchases before buying, thus leading to an informed customer who is ready to buy.
* Allows for mailing lists to send the same email message to hundreds of customers for the same cost as sending to one. No more huge postal costs, or licking envelopes.
* Can provide answers to frequently asked questions, which reduces the costs of staff having to answer the same thing over and over.
* Provides a shopping experience that is both convenient and timesaving. (And for women, satisfying!)
* Gives your business a great advantage over your competitors and consequently provides an opportunity to capture their market share.
* Doesn’t limit a business to its location; you can reach a wider and more diversified market.
* Makes it easy to collect and collate information on the purchasing patterns of your customers, thereby allowing a vendor to cost effectively alter their sales and promotion methods.
* Can accept automated orders and payments for products.
* Can facilitate an online database of products, which is quick and easy to modify; whereas traditional media catalogues cannot be altered without great expense.

What is jQuery

jQuery is an amazing JavaScript library that makes it easy to create wonderful web effects in just a few lines of code. As the website says:”

“jQuery is a JavaScript library that takes this motto to heart: Writing JavaScript code should be fun. jQuery achieves this goal by taking common, repetitive, tasks, stripping out all the unnecessary markup, and leaving them short, smart and understandable.”

Maybe you are thinking… “Why I would need another JavaScript library”? Just give a try and you will see how simple and powerful it is even if you have already used Moo.fx, Scriptaculous, TW-SACK or Prototype.
Why I should use jQuery?

Simple. In just one glance at the source code of a page using jQuery you’ll see how easy it is to use, how much it accomplishes in so few lines of code, and how graceful it is.

My mind was opened one day when I stumbled across some code written with jQuery. I was flipping through the RSS feeds and reading my daily dose of web design blogs when I came across an example of JavaScript loveliness that used jQuery. Truth be told, the code on that site had some browser related bugs… but the concept was something I hadn’t seen before.
What about the code?

The code looked almost simple. Like nothing I had seen before. It made sense.

I started reading through the documentation and was amazed to see how much could be done with so little extra code.
When you can use jQuery?

You should use jQuery when you need:

* A small library that gives you powerful control over the Document Object Model
* With very little effort or work on your part

Or

* Quick access to AJAX
* Without a lot of bloat (overhead - wasted code)
* And some basic animation effects to spice things up

But…

If you need super fancy effects for animation, drag and drop, and super smooth animation then you’ll probably want to use Prototype and one of the many great library created to enhance the effects.
Where to get it?

You can download the source code (15k), a lot of plugins and read some excellent tutorials at the jQuery website. jQuery was created by John Resig.