The well-known ports are those from 0 through 1023. Examples include:
mkdir - make directoriesa
Usage
mkdir [OPTION] DIRECTORY
Options
Create the DIRECTORY(ies), if they do not already exist.
Mandatory arguments to long options are mandatory for short options too.
-m, mode=MODE set permission mode (as in chmod), not rwxrwxrwx - umask
-p, parents no error if existing, make parent directories as needed
-v, verbose print a message for each created directory
-help display this help and exit
-version output version information and exit
cd - change directories
Use cd to change directories. Type cd followed by the name of a directory to access that directory.Keep in mind that you are always in a directory and can navigate to directories hierarchically above or below.
mv- change the name of a directory
Type mv followed by the current name of a directory and the new name of the directory.
Ex: mv testdir newnamedir
pwd - print working directory
will show you the full path to the directory you are currently in. This is very handy to use, especially when performing some of the other commands on this page
rmdir - Remove an existing directory
rm -r
Removes directories and files within the directories recursively.
chown - change file owner and group
Usage
chown [OPTION] OWNER[:[GROUP]] FILE
chown [OPTION] :GROUP FILE
chown [OPTION] --reference=RFILE FILE
Options
Change the owner and/or group of each FILE to OWNER and/or GROUP. With --reference, change the owner and group of each FILE to those of RFILE.
-c, changes like verbose but report only when a change is made
-dereference affect the referent of each symbolic link, rather than the symbolic link itself
-h, no-dereference affect each symbolic link instead of any referenced file (useful only on systems that can change the ownership of a symlink)
-from=CURRENT_OWNER:CURRENT_GROUP
change the owner and/or group of each file only if its current owner and/or group match those specified here. Either may be omitted, in which case a match is not required for the omitted attribute.
-no-preserve-root do not treat `/' specially (the default)
-preserve-root fail to operate recursively on `/'
-f, -silent, -quiet suppress most error messages
-reference=RFILE use RFILE's owner and group rather than the specifying OWNER:GROUP values
-R, -recursive operate on files and directories recursively
-v, -verbose output a diagnostic for every file processed
The following options modify how a hierarchy is traversed when the -R option is also specified. If more than one is specified, only the final one takes effect.
-H if a command line argument is a symbolic link to a directory, traverse it
-L traverse every symbolic link to a directory encountered
-P do not traverse any symbolic links (default)
chmod - change file access permissions
Usage
chmod [-r] permissions filenames
r Change the permission on files that are in the subdirectories of the directory that you are currently in. permission Specifies the rights that are being granted. Below is the different rights that you can grant in an alpha numeric format.filenames File or directory that you are associating the rights with Permissions
u - User who owns the file.
g - Group that owns the file.
o - Other.
a - All.
r - Read the file.
w - Write or edit the file.
x - Execute or run the file as a program.
Numeric Permissions:
CHMOD can also to attributed by using Numeric Permissions:
400 read by owner
040 read by group
004 read by anybody (other)
200 write by owner
020 write by group
002 write by anybody
100 execute by owner
010 execute by group
001 execute by anybody
ls - Short listing of directory contents
-a list hidden files
-d list the name of the current directory
-F show directories with a trailing '/'
executable files with a trailing '*'
-g show group ownership of file in long listing
-i print the inode number of each file
-l long listing giving details about files and directories
-R list all subdirectories encountered
-t sort by time modified instead of name
cp - Copy files
cp myfile yourfile
Copy the files "myfile" to the file "yourfile" in the current working directory. This command will create the file "yourfile" if it doesn't exist. It will normally overwrite it without warning if it exists.
cp -i myfile yourfile
With the "-i" option, if the file "yourfile" exists, you will be prompted before it is overwritten.
cp -i /data/myfile
Copy the file "/data/myfile" to the current working directory and name it "myfile". Prompt before overwriting the file.
cp -dpr srcdir destdir
Copy all files from the directory "srcdir" to the directory "destdir" preserving links (-poption), file attributes (-p option), and copy recursively (-r option). With these options, a directory and all it contents can be copied to another dir
ln - Creates a symbolic link to a file.
ln -s test symlink
Creates a symbolic link named symlink that points to the file test Typing "ls -i test symlink" will show the two files are different with different inodes. Typing "ls -l test symlink" will show that symlink points to the file test.
locate - A fast database driven file locator.
slocate -u
This command builds the slocate database. It will take several minutes to complete this command.This command must be used before searching for files, however cron runs this command periodically on most systems.locate whereis Lists all files whose names contain the string "whereis". directory.
more - Allows file contents or piped output to be sent to the screen one page at a time
less - Opposite of the more command
cat - Sends file contents to standard output. This is a way to list the contents of short files to the screen. It works well with piping.
whereis - Report all known instances of a command
wc - Print byte, word, and line countsbg
bg jobs Places the current job (or, by using the alternative form, the specified jobs) in the background, suspending its execution so that a new user prompt appears immediately. Use the jobs command to discover the identities of background jobs.
cal month year - Prints a calendar for the specified month of the specified year.
cat files - Prints the contents of the specified files.
clear - Clears the terminal screen.
cmp file1 file2 - Compares two files, reporting all discrepancies. Similar to the diff command, though the output format differs.
diff file1 file2 - Compares two files, reporting all discrepancies. Similar to the cmp command, though the output format differs.
dmesg - Prints the messages resulting from the most recent system boot.
fg
fg jobs - Brings the current job (or the specified jobs) to the foreground.
file files - Determines and prints a description of the type of each specified file.
find path -name pattern -print
Searches the specified path for files with names matching the specified pattern (usually enclosed in single quotes) and prints their names. The find command has many other arguments and functions; see the online documentation.
finger users - Prints descriptions of the specified users.
free - Displays the amount of used and free system memory.
ftp hostname
Opens an FTP connection to the specified host, allowing files to be transferred. The FTP program provides subcommands for accomplishing file transfers; see the online documentation.
head files - Prints the first several lines of each specified file.
ispell files - Checks the spelling of the contents of the specified files.
kill process_ids
kill - signal process_ids
kill -l
Kills the specified processes, sends the specified processes the specified signal (given as a number or name), or prints a list of available signals.
killall program
killall - signal program
Kills all processes that are instances of the specified program or sends the specified signal to all processes that are instances of the specified program.
mail - Launches a simple mail client that permits sending and receiving email messages.
man title
man section title - Prints the specified man page.
ping host - Sends an echo request via TCP/IP to the specified host. A response confirms that the host is operational.
reboot - Reboots the system (requires root privileges).
shutdown minutes
shutdown -r minutes
Shuts down the system after the specified number of minutes elapses (requires root privileges). The -r option causes the system to be rebooted once it has shut down.
sleep time - Causes the command interpreter to pause for the specified number of seconds.
sort files - Sorts the specified files. The command has many useful arguments; see the online documentation.
split file - Splits a file into several smaller files. The command has many arguments; see the online documentation
sync - Completes all pending input/output operations (requires root privileges).
telnet host - Opens a login session on the specified host.
top - Prints a display of system processes that's continually updated until the user presses the q key.
traceroute host - Uses echo requests to determine and print a network path to the host.
uptime - Prints the system uptime.
w - Prints the current system users.
wall - Prints a message to each user except those who've disabled message reception. Type Ctrl-D to end the message.
While thinking about a programming language deficiency, I rediscovered polymorphism. Overloading a function allows a function call to behave differently when passed variables of different type. I was trying to devise a method of simulating function overloading, because PHP does not support it. I considered implementing a function with an if-else statement ladder that tests the type of the actual argument and executes statements that correspond to the argument’s type. This technique may ultimately result in a monolithic function or a function implementation that is too knowledgeable of multiple class hierarchies. Rethinking a problem that I was hoping to solve with function overloading allowed me to accept the lack of this language feature and think of other techniques.
There are two problems that arise from the if-else statement ladder approach. The implementation of such a function would require the function to have knowledge of every data type to be used with it. This problem can be extended to knowing class hierarchies, if subclassing is involved. This means that an introduction of a new data type to be processed by the function would require the function to be modified, which creates the possibility that the modification will break other existing code that relies on the function. The second problem is having the function’s maintainer think about how the function should operate on the different data types that can be passed to it. This responsibility is better placed on the people who maintain the different data types.
One solution that deals with the problems in the if-else statement ladder is polymorphism. Polymorphism allows a set of heterogeneous elements to be treated identically. It is achieved through inheritance. In PHP, interface inheritance and implementation inheritance can be written explicitly through the use of interfaces and class extensions, respectively. Interfaces specify a class interface without providing an implementation. Classes from different class hierarchies can implement an interface, and in this way, it can be seen as different from abstract classes. When a class is defined to implement an interface, the language enforces a rule that the class implements all features of the interface. A method that operates on an interface will accept an object of any class that implements the interface, and it will function correctly.
Here is a toy example of interface inheritance, polymorphism, and PHP type hinting:
color = $color;
}
public function getColor()
{
return $this->color;
}
}
class Rectangle extends Shape implements HasArea
{
private $w;
private $h;
public function __construct( $color, $w, $h )
{
parent::__construct($color);
$this->w = $w;
$this->h = $h;
}
public function area()
{
return ($this->w * $this->h);
}
public function areaUnit()
{
if( $this->area() > 1 )
return "square meters";
else
return "square meter";
}
}
class Territory implements HasArea
{
private $name;
public function __construct( $name )
{
$this->name = $name;
/* not used in this example... */
}
public function area()
{
return 5;
}
public function areaUnit()
{
return "cities";
}
}
function outputArea( HasArea $ha )
{
echo "The area is: "
. " {$ha->area()} {$ha->areaUnit()}\n";
}
$HAs = array(
new Rectangle("red",2,3),
new Territory( "somename" )
);
foreach( $HAs as $HA )
{
outputArea( $HA );
}
?>Type hints help the PHP interpreter enforce the restriction that outputArea() operates only on objects of data types that implement the HasArea interface. Rectangle and Territory are from unrelated class hierarchies. outputArea() can operate on these classes, since these classes implement the HasArea interface.
The explored method accomplishes only some of the features offered by function overloading. In the above example, outputArea() was restricted to one argument. In some programming languages, a function can be overloaded on the number of arguments along with the types of those arguments and the order that those types appear in the argument list. This method, however, was useful in a problem I considered solving with function overloading.
• Familiarity
• Simplicity
• Efficiency
• Security
• Flexibility
One final characteristic makes PHP particularly interesting: it’s free!
Programmers from many backgrounds will find themselves already accustomed to the PHP language. Many of the language’s constructs are borrowed from C and Perl, and in many cases PHP code is almost indistinguishable from that found in the typical C or Pascal program. This minimizes the learning curve considerably.
A PHP script can consist of 10,000 lines or one line: whatever you need to get the job done. There is no need to include libraries, special compilation directives, or anything of the sort. The PHP engine simply begins executing the code after the first escape sequence (). If the code is syntactically correct, it will be executed exactly as it is displayed.
EfficiencyEfficiency is an extremely important consideration for working in a multiuser environment such as the WWW. PHP 4.0 introduced resource allocation mechanisms and more pronounced support for object-oriented programming, in addition to session management features. Reference counting has also been introduced in the latest version, eliminating unnecessary memory allocation
SecurityPHP provides developers and administrators with a flexible and efficient set of security safeguards. These safeguards can be divided into two frames of reference: system level and application level.
System-Level Security SafeguardsPHP furnishes a number of security mechanisms that administrators can manipulate,providing for the maximum amount of freedom and security when PHP is properly configured. PHP can be run in what is known as safe mode, which can limit users’ attempts to exploit the PHP implementation in many important ways. Limits can also be placed on maximum execution time and memory usage, which if not controlled can have adverse affects on server performance. Much as with a cgi-bin folder, administrators can also place restrictions on the locations in which users can view and execute PHP scripts and use PHP scripts to view guarded server information, such as the passwd file.
Application-Level Security SafeguardsSeveral trusted data encryption options are supported in PHP’s predefined function set. PHP is also compatible with many third-party applications, allowing for easy-integration with secure ecommerce technologies. Another advantage is that the PHP source code is not viewable through the browser because the script is completely parsed before it is sent back to the requesting user. This benefit of PHP’s server-side architecture prevents the loss of creative scripts to users at least knowledgeable enough to execute a ‘View Source’.
Because PHP is an embedded language, it is extremely flexible towards meeting the needs of the developer. Although PHP is generally touted as being used in conjunction solely with HTML, it can also be integrated alongside languages like JavaScript, WML, XML, and many others. Additionally, as with most other mainstream languages, wisely planned PHP applications can be easily expanded as needed. Browser dependency is not an issue because PHP scripts are compiled entirely on the server side before being sent to the user. In fact, PHP scripts can be sent to just about any kind of device containing a browser, including cell phones, personal digital assistant (PDA) devices, pagers, laptops, not to mention the traditional PC. People who want to develop shell-based applications can also execute PHP from the command line.Since PHP contains no server-specific code, users are not limited to a specific and perhaps unfamiliar Web server. Apache, Microsoft IIs, Netscape Enterprise Server, Stronghold, and Zeus are all fair game for PHP’s server integration. Because of the various platforms that these servers operate on, PHP is largely platform independent, available for such platforms as UNIX, Solaris, FreeBSD, and Windows 95/98/NT.
Finally, PHP offers access to external components, such as Enterprise Java Beans and Win32 COM objects. These newly added features put PHP in the big league, truly enabling developers to scale PHP projects upward and outward as need be.
The open source development strategy has gained considerable notoriety in the software industry. The prospect of releasing source code to the masses has resulted in undeniably positive outcomes for many projects, perhaps most notably Linux, although the success of the Apache project has certainly been a major contributor in proving the validity of the open source ideal. The same holds true for the developmental history of PHP, as users worldwide have been a huge factor in the advancement of the PHP project.
PHP’s embracing of this open source strategy result in great performance gains for users, and the code is available free of charge. Additionally, an extremely receptive user community numbering in the thousands acts as “customer support,” providing answers to even the most arcane questions in popular online discussion groups.
The most hyped framework. Why not; it’s by Zend which develops PHP itself. It has just got out of beta. You will also find it is rich with features too. It was also the fastest. No doubt it has all the corporate stuffs but I still felt it’s a bit tough. Just a little too much for most. It doesn’t have PHP 4 too. But it will definitely more provide support and professional code being backed by a corporate company. This is for those who want to build apps for big enterprises. They will have pro coders and will also be benefited from the components it provides.
CakePHP is a rapid development framework for PHP that provides an extensible architecture for developing, maintaining, and deploying applications. Using commonly known design patterns like MVC and ORM within the convention over configuration paradigm, CakePHP reduces development costs and helps developers write less code.
Yii – a high-performance component-based PHP framework best for developing large-scale Web applications. Yii comes with a full stack of features, including MVC, DAO/ActiveRecord, I18N/L10N, caching, jQuery-based AJAX support, authentication and role-based access control, scaffolding, input validation, widgets, events, theming, Web services, and so on. Written in strict OOP, Yii is easy to use and is extremely flexible and extensible.
CodeIgniter is a powerful PHP framework with a very small footprint, built for PHP coders who need a simple and elegant toolkit to create full-featured web applications. If you’re a developer who lives in the real world of shared hosting accounts and clients with deadlines, and if you’re tired of ponderously large and thoroughly undocumented frameworks.
Symfony is a full-stack framework, a library of cohesive classes written in PHP5. It provides an architecture, components and tools for developers to build complex web applications faster. Choosing symfony allows you to release your applications earlier, host and scale them without problem, and maintain them over time with no surprise. Symfony is based on experience. It does not reinvent the wheel: it uses most of the best practices of web development and integrates some great third-party libraries.
PRADOTM is a component-based and event-driven programming framework for developing Web applications in PHP 5. PRADO stands for PHP Rapid Application Development Object-oriented.
The Zoop Framework: PHP development without the suck. The Zoop Framework is inclusive, cooperating with and containing components integrated from some existing projects including Smarty, the Prototype JS Framework, and a number of Pear Modules.
xAjax is an open source PHP class library that allows to create quickly Ajax applications using HTML, CSS, JavaScript, and PHP.
Kohana is a PHP 5 framework that uses the model view controller architectural pattern. It aims to be secure, lightweight, and easy to use.
BlueShoes is a comprehensive application framework and content management system. It is written in the widely used web-scripting language PHP. BlueShoes offers excellent support for the popular MySQL database as well as support for Oracle and MSSQL.
Limb is an OpenSource(LGPL) PHP framework mostly aimed for rapid web application prototyping and development. The current actively developed branch of framework is Limb3(there is also Limb2 but it’s not maintained anymore).
