<?php
/
Connects to packstormsecurity.org and created a
atom feed of the last 20 uploaded files.
@requires php-curl php-tidy
@author Tully Rankin
@url http://www.TullyRankin.com
/
$ch = curlinit();
$url = 'http://www.packetstormsecurity.org/last20.html';
$site = 'http://www.packetstormsecurity.org';
curlsetopt($ch, CURLOPTURL, $url);
curlsetopt($ch, CURLOPTHEADER, 0);
curlsetopt($ch, CURLOPTRETURNTRANSFER, 1);
$data = curlexec($ch);
curlclose($ch);
$tidyconfig = array(
'clean' => true,
'output-xhtml' => true,
'show-body-only' => false,
'wrap' => 0
);
$tidy = tidyparsestring($data, $tidyconfig, 'UTF8');
$tidy->cleanRepair();
$xhtml = pregreplace('/\<spacer.*\>/','',$tidy);
$xml = new DOMDocument();
$xml->loadHTML($xhtml);
$body = $xml->getElementsByTagName("body")->item(0);
$links = $body->getElementsByTagName("a");
$x = 0;
foreach($links as $link)
{
if ($link->getAttribute("class") == "fname")
{
$files[$x]['name'] = $link->nodeValue;
$files[$x]['link'] = $link->getAttribute("href");
$x++;
}
}
$tables = $body->getElementsByTagName("table");
foreach ($tables as $table)
{
if ($table->getAttribute("class") != "fbox2") continue;
$tRows = $table->getElementsByTagName("tr");
foreach($tRows as $row)
{
if ($row->getAttribute("class") == "finfo")
{
if ($row->getElementsByTagName("td")->item(1) != null &&
$row->getElementsByTagName("td")->item(1)->getAttribute("valign") == "top")
{
$td = $row->getElementsByTagName("td")->item(1);
$text[] = $td->nodeValue;
}
}
}
}
$x = 0;
$fileNames = array();
foreach ($files as $file)
{
if (substr($file['link'],0,1) == "/")
{
$content[$x]['name'] = $file['name'];
$content[$x]['link'] = $site.$file['link'];
$content[$x]['text'] = $text[$x];
$x++;
}
}
$result = '<?xml version="1.0" encoding="utf-8"?>
<feed xmlns="http://www.w3.org/2005/Atom">
<title>PacketStorm Security</title>
<link rel="alternate" type="text/html" href="http://www.tullyrankin.com/" />
<link rel="self" type="application/atom+xml" href="http://www.tullyrankin.com/atom.xml" />
<id></id>
<updated>2010-03-03</updated>
<subtitle>Security Feed</subtitle>
';
foreach ($content as $node)
{
$result .= "<entry>";
$result .= "<title>{$node['name']}</title>";
$result .= "<link href=\"{$node['link']}\" />";
$result .= "<summary>{$node['text']}</summary>";
$result .= "</entry>";
}
$result .= "</feed>";
$conn = @fopen('packetstorm.xml','w+');
if (@fwrite($conn, $result) === false)
{
die('<h1>Could Not create feed</h1>');
}
else
{
echo '<h1>Created new packetstorm.xml file!</h1>';
}
fclose($conn);
]]>
<html>
<head>
<title>Simple Ajax Example</title>
<script type="text/javascript">
var xmlhttp;
function showUser(str) {
xmlhttp=GetXmlHttpObject();
if (xmlhttp==null)
{
alert ("Browser does not support HTTP Request");
return;
}
var url="getNames.php";
url=url+"?name="+str.value;
url=url+"&nocache="+Math.random();
xmlhttp.onreadystatechange=stateChanged;
xmlhttp.open("GET",url,true);
xmlhttp.send(null);
}
function stateChanged() {
if (xmlhttp.readyState==4)
{
document.getElementById("nameHint").innerHTML=xmlhttp.responseText;
}
}
function GetXmlHttpObject() {
if (window.XMLHttpRequest)
{
// code for IE7+, Firefox, Chrome, Opera, Safari
return new XMLHttpRequest();
}
if (window.ActiveXObject)
{
// code for IE6, IE5
return new ActiveXObject("Microsoft.XMLHTTP");
}
return null;
}
</script>
</head>
<body>
<form name="formName" id="formName">
<input type="text" name="name" id="name" onKeyUp="showUser(this)">
</form>
<span id="nameHint" name="nameHint"></span>
</body>
</html>
<?php
$name = striptags($GET['name']);
if (!empty($name))
{
if ($con = mysqlconnect('127.0.0.1', 'root', '1234'))
{
if (!mysqlselectdb('test'))
{
echo 'Could not connect to database';
exit;
}
$sql = sprintf("SELECT name FROM names WHERE name like '%s'",
mysqlrealescapestring($name.'%'));
$result = mysqlquery($sql,$con);
if (!$result)
{
echo 'Bad Query';
}
$rowCount = mysqlnumrows($result);
while ($row = mysqlfetch_assoc($result))
{
$names[] = $row['name'];
}
}
}
if (count($names) > 0)
{
echo '<ul>';
foreach ($names as $name)
{
echo "<li>$name</li>";
}
echo '</ul>';
}
As you can see, the getNames.php file first looks at the GET value for the name Parameter. I also have it wrapped in the striptags function
which will eliminate the chance of a user entering any kind of tags
that may end up breaking or altering the script. Next, I check to see
if the $name value is empty. The script will not display anything if the $name value is empty or there is no results. Now the script can connect to a mysql server and select the correct DB. Now I write
the query using the sprintf function. This allows me to alter multiple
variables in the string. I use the %s for string and have
mysqlrealescapestring function return the $name variable. The
mysqlrealescape_string prepends backslashes to the following
characters "\x00, \n, \r, \, ', " and \x1a".
I now query the database with the $sql string that I just created. I
create the variable rowCount which will return the # of rows returned
from the query. Next we loop through the results and add each name to
the $names variable.
We now have all the results in an array and need to display the result. I first check to see if the array is not empty. I do this by using the count() function on the $names array. If the count is greater then 0 we will display each of the rows returned in a unordered list <ul> tag.
This is by far the simplest AJAX example. We could have returned the results as JSON and looped through them better in the index.php page. I will write a more technical and more advanced example in the near future.
<p>
<form action="#" method="get">
<input type="text" name="url" value="YOUTUBE URL">
<input type="submit" name="submit" value="Get Embed Code">
</form>
</p>
<?php
if ($GET['url'] != "") {
$url = filegetcontents($GET['url']);
$url = pregmatch('/(input id="embed).*(\/>)/', $url, $arr);
$url = pregmatch('/(<).(\/object>)/',$arr[0], $result);
$result = html_entity_decode($result[0]);
echo '<b>The Video...</b><br />';
echo $result . '<br /><br />';
echo '<b>The embed code...</b><br />';
echo htmlentities($result) . '<br /><br />';
}
?>
<br />
<b>How to get the embed code from the linux Command line.</b>
<br />curl 'http://www.youtube.com/watch?v=vFMh2oeob18' | egrep '((input id="embed)./>)' | egrep -o '(<).*(/object>)'
]]>
<?php
/
Example of Decorator Pattern in PHP
/
class ReadStr {
protected $str;
function construct($str) {
$this->str = $str;
}
function display() {
return $this->str;
}
}
class StrDecorator extends ReadStr {
protected $str;
protected $readStr;
function construct(ReadStr $readStr) {
$this->readStr = $readStr;
$this->str = $this->readStr->display();
}
function display() {
return $this->str;
}
}
class StrToUpperDecorator extends StrDecorator {
private $strDecorator;
function construct(StrDecorator $strDecorator) {
$this->strDecorator = $strDecorator;
$this->stringToUpper();
}
function stringToUpper() {
$this->strDecorator->str = strtoupper($this->strDecorator->str);
}
}
class StrReverseDecorator extends StrDecorator {
private $strDecorator;
function construct(StrDecorator $strDecorator) {
$this->strDecorator = $strDecorator;
$this->stringReverse();
}
function stringReverse() {
$this->strDecorator->str = strrev($this->strDecorator->str);
}
}
$readStr = new ReadStr('Decorator Pattern!');
$decorator = new StrDecorator($readStr);
echo $decorator->display() . "\n";
$strToUpper = new StrToUpperDecorator($decorator);
echo $decorator->display() . "\n";
$strReverse = new StrReverseDecorator($decorator);
echo $decorator->display();
print "Enter string to encode:";
$str=<STDIN>;chomp $str;
$enc = encode($str); print "Hex Encoded value: 0x$enc\n";
sub encode{ #Sub to encode
@subvar=@;
my $sqlstr =$subvar[0];
@ASCII = unpack("C*", $sqlstr);
foreach $line (@ASCII) {
$encoded = sprintf('%lx',$line);
$encodedcommand .= $encoded;
}
return $encoded_command;
}
]]>
<?php
if ($argc > 1) {
echo "This script does not take any arguments.\n";
exit;
}
function read ($length='255') {
if (!isset ($GLOBALS['StdinPointer'])) {
$GLOBALS['StdinPointer'] = fopen ("php://stdin","r");
}
$line = fgets ($GLOBALS['StdinPointer'],$length);
return trim ($line);
}
echo "\n";
echo "Enter Mail Server IP Address: ";
$host = read(30) . "\n";
echo "RCPT: ";
$rcpt = read(40) . "\n";
echo "Mail From: ";
$from = read(40) . "\n";
echo "Subject: ";
$subject = read(25) . "\n";
echo "Message: ";
$message = read(500) . "\n";
if ( (strlen($host) < 5) || (strlen($rcpt) < 10) ||
(strlen($from) < 10) || (strlen($subject) < 2) ||
(strlen($message) < 5) ) {
echo "You need to enter all fields properly.\n";
exit;
}
$fp = fsockopen($host,25,$errstr,$errno,100);
if (!$fp) {
echo "$errstr ($errno)";
} else {
$out = "helo h4x0r\r\n";
$out .= "mail from:$from\r\n";
$out .= "rcpt to:$rcpt\r\n";
$out .= "data\r\n";
$out .= "Subject:$subject\r\n\r\n";
$out .= "$message\r\n.\r\n";
fwrite($fp, $out);
fclose($fp);
}
?>
<?php
if ($argc < 4) {
echo "
---------------------------------------------------\n
HTTP Check Headers Script (Written by Tully Rankin)\n
Usage: headers.php [site] [get|head|options] file\n
Example: headers.php www.example.com get /\n
---------------------------------------------------
";
exit;
} else {
$site = $argv[1];
}
$request = strtolower($argv[2]);
$file = $argv[3];
if ($request == "get") {
$out = "GET $file HTTP/1.1\r\n";
$out .= "Host: $site\r\n";
$out .="Connection: Close\r\n\r\n";
} else if ($request == "options") {
$out = "OPTIONS $file HTTP/1.1\r\n";
$out .= "Host: $site\r\n";
$out .="Connection: Close\r\n\r\n";
} else if ($request == "head") {
$out = "HEAD $file HTTP/1.1\r\n";
$out .= "Host: $site\r\n";
$out .="Connection: Close\r\n\r\n";
} else {
echo "Incorrect Request Type\n";
exit;
}
$fp = fsockopen($site,80,$errstr,$errno,30);
if (!$fp) {
echo "$errstr ($errno)";
} else {
fwrite($fp, $out);
while (!feof($fp)) {
echo fgets($fp, 1024);
}
fclose($fp);
}
?>
<?php
$host = "www.google.com";
$port = 80;
$pages = array("/cgi-bin","/admin","/test","/beta");
foreach ($pages as $page) {
$fp = fsockopen($host,$port,$errno,$errstr,30);
if (!$fp) {
echo "$errstr ($errno)";
} else {
$out = "GET $page HTTP/1.1\r\n";
$out.= "Host: $host\r\n";
$out .= "Connection: Close\r\n\r\n";
fwrite($fp,$out);
while (!feof($fp)) {
$data = fread($fp, 20);
if (strstr($data,'HTTP/1.1')) {
echo " Site: $host \n Page: $page \n Code: $data \n\n";
}
}
unset($data);
unset($out);
fclose($fp);
}
}
?>
All HTTP messages (requests and responses) consist of one or more headers, each on a separate line, followed by a mandatory blank line, followed by an optional message body.
The first line of every HTTP request consists of three
items, separated by spaces:
HTTP Responses
The first line of every HTTP response consists of three items, separated by spaces:
HTTP Methods
The two main methods are GET and POST. There are others such as the following:
[NOTE]
The correct technical term for a URL is actually URI (or uniform resource identifier), but his term is really only used in formal specifications.)
HTTP Headers
General Headers
Request Headers
Response Headers
Cookies
Status Codes
Each HTTP response message must contain a status code in its first line, indicating the result of the request. The status codes fall into five groups, accoding to the first digit of the code.
1xx - Informational.
2xx - The request was successful.
3xx - The client is redirected to a different resource.
4xx - The request contains an error of some kind.
5xx - The server encountered an error fulfilling the request.
Some of the common Status Codes you will encounter when trying to hack a web application are as follows:
100 Continue - This response is sent in some circumstances when a client submits a request containing a body. The response indicates that the request headers were received and that the client should continue sending the body. The server will then return a second response when the request has been completed.
200 Ok - This indicates that the request was successful and the response body contains the result of the request.
201 Created - This is returned in response to a PUT request to indicate that the request was successful.
301 Moved Permanently - This redirects the browser permanently to a different URL, which is specified in the Location header. The client should use the new URL in the future rather than the original.
302 Found - This redirects the browser temporarily to a different URL, which is specified in the Location header. The client should revert to the original URL in subsequent requests.
304 Not Modified - This instructs the browser to use its cached copy of the requested resource. The server uses the If-Modified-Since and If-None-Match request headers to determine whether the client has the latest version of the resource.
400 Bad Request - This indicates that the client submitted an invalid HTTP request. You will probably encounter this when you have modified a request in certain invalid ways, for example by placing a space character into the URL.
401 Unauthorized - The server requires HTTP authentication before the request will be granted. The WWW-Authenticate header contains details of the type(s) of authentication supported.
403 Forbidden - This indicates that no one is allowed to access the requested resource, regardless of authentication.
404 Not Found - This indicates that the requested resource does not exist.
405 Method Not Allowed - This indicates that the method used in the request is not supported for the specified URL. For example, you may receive this status code if you attempt to use the PUT method where it is not supported.
413 Request Entity Too Large - If you are probing for buffer overflow vulnerabilities in native code, and so submitting long strings of data, this indicates that the body of your request is too large for the server to handle.
414 Request URI Too Long - Similar to the previous response, this indicates that the URL used in the request is too large for the server to handle.
500 Internal Server Error - This indicates that the server encountered an error fulfilling the request. This normally occurs when you have submitted unexpected input that caused an unhandled error somewhere within the application's processing. You should review the full contents of the server's response closely for any details indicating the nature of the error.
503 Service Unavailable - This normally indicates that, although the web server itself Is functioning and able to respond to requests, the application accessed via the server is not responding. You should verify whether this is the result of any action that you have performed.
[NOTE]
SSL has now strictly been superseded by transport layer security (TLS), but the latter is still normally referred to using the older name.
HTTP Authentication
The HTTP protocol includes its own mechanisms for authenticating users, using various authentication schemes, including:
Basic - This is a very simple authentication mechanism that sends user credentials as a Base64-encoded string in a request header with each message.
NTLM - This is a challenge-response mechanism and uses a version of the Windows NTLM protocol.
Digest - This is a challenge-response mechanism and uses MD5 checksums of a nonce with the user's credentials.
String Functions
|
Function |
What it does |
Example |
|
Concatenation |
Add's strings together. |
$x . $t |
|
Addslashes($str) |
Returns a string with backslashes before characters that need to be quoted in database queries etc. These characters are single quote ('), double quote ("), backslash (\) and NUL (the NULL byte). |
string addslashes ( string $str ) |
|
Rtrim($x) |
rtrim -- Strip whitespace (or other characters) from the end of a string |
string rtrim ( string $str [, string $charlist ] ) |
|
Ltrim($x) |
Strip whitespace (or other characters) from the
beginning of a string. |
string ltrim ( string $str [, string $charlist ] ) |
|
Strlen($x) |
Returns the length of the given string . |
int strlen ( string $string ) |
|
Strpos($str,$x) |
Find position of first occurrence of a string |
int strpos ( string $haystack , mixed $needle [, int $offset= 0 ] ) |
|
Explode($d,$str) |
explode -- Split a string by string |
array explode ( string $delimiter , string $string [, int $limit ] ) |
|
implode($d,$str) |
Join array elements with a string. |
string implode ( string $glue , array $pieces ) |
|
Soundex($str) |
Calculate the soundex key of a
string. |
string soundex
( string $str ) |
|
Metaphone($str) |
Calculate the metaphone key of a
string |
string metaphone ( string $str [, int $phones= 0 ] ) |
Regular Functions
|
Function |
Description |
Example |
|
Ereg($p,$str,[$m]) |
Regular expression match |
int ereg ( string $pattern , string $string [, array &$regs ] ) int eregi ( string $pattern , string $string [, array &$regs ] ) |
|
Eregi($p,$str, [$m]) |
Case insensitive regular expression match |
int eregi ( string $pattern , string $string [, array &$regs ] )
|
|
Ereg_replace($p,$r,$str) |
Replace regular expression |
string ereg_replace ( string $pattern , string $replacement , string $string ) |
|
Sql_regcase($p) |
Make regular expression for case insensitive match |
string sql_regcase ( string $string ) |
|
|
Split string into array by regular expression |
array split ( string $pattern , string $string [, int $limit ] ) |
|
Preg_match() |
Perform a regular expression match |
int preg_match ( string $pattern , string $subject [, array &$matches [, int $flags [, int $offset ]]] ) |
|
Preg_match_all() |
Perform a global regular expression match |
int preg_match_all ( string $pattern , string $subject , array &$matches [, int $flags [, int $offset ]] ) |
|
Preg_replace() |
Perform a regular expression search and replace |
mixed preg_replace ( mixed $pattern , mixed $replacement , mixed $subject [, int $limit= -1 [, int &$count ]] ) |
|
Preg_split() |
Split string by a regular expression |
array preg_split ( string $pattern , string $subject [, int $limit= -1 [, int $flags= 0 ]] ) |
MetaCharacters
|
. |
Any ONE Character |
|
[A-Z0-9] |
Any one of the chars |
|
[^a-cx-z] |
Not one of the chars |
|
^ |
Begins with |
|
$ |
End with |
|
X{2} |
2 consecutive "x" |
|
X{2,5} |
Between 2 and 5 consecutive "x" |
|
X? |
0 or 1 "x" |
|
X+ |
1 or more "x" |
|
\d |
Digit |
|
\D |
Non-digit |
|
\w |
Word |
|
\W |
Non-word |
|
\s |
Space char |
|
\S |
Not a space char |
|
(x|z) |
X or Z |
Bootloader Phase
The bootloader is software that the BIOS can load from the MBR of the hard that will allow the CPU to access the disk and load the operating system into RAM. The do this, the bootloader is configured with the location of the operating system files on the hard disk drive.
After loading the bootloader software into memory, the BIOS turns control of the ystem over to the bootloader.
With later Linux kernels, the bootloader may also create a temporary, virtual file system in your system RAM called a ramdisk. This file system is called initrd image.
The term "initrd" stands for initial ramdisk.
This image contains a basic file system that can be used to complete a variety of startup taks. The reason the initrd iamge is used is because Linux systems can use a wide variety of devices for the root (/) file system.
Kernal Phase
After the kernel loads, several key things happen, including the following:
Lilo Bootloader
The bootloader configuration file for LILO is found in /etc/lilo.conf
The following are options in the configuration file:
|
Section |
Option |
Description |
|
Global Options |
menu -scheme |
Describes the colors used in the LILO boot menu. The system is: Text_color:highlight_color:border_color:title_color You use 2 values for each section. The first is the forground color and the second is the background color. |
|
|
Timeout |
Sets the timeout period in 1/10th seconds before the default menu item is automatically run. The default is usually 80 which gives the user 8 seconds to select a menu item. |
|
|
Lba32 |
Tells lilo to ignore the hard drive's physical geometry and use logical block addressing. This allows LILO to work with disks that have more than 1023 cylinders (which all modern hard drive do). |
|
|
Change-rules |
Defines boot-time changes to partition type numbers. |
|
|
Reset |
Specifies that all default change-rules are removed. |
|
|
Read-only |
Specifies that the rool (/) file system be mounted read-only at first. After checking the integrity of the file system, the kernel will usually remount the file system in read-write mode. |
|
|
Prompt |
Specifies that the boot: prompt be displayed. |
|
|
Default |
Specifies the default image that will be loaded if the user doesn't make a selection. |
|
|
Message |
Specifies the location of the image file that LILO will display. |
|
|
Boot |
Specifies the device that contains the boot sector. |
|
Image Options |
Image |
Specifies the path to the boot image of a Linux kernel. |
|
|
Label |
Specifies a name for the image. |
|
|
Append |
Appends the specified options to the parameters that are passed to the kernel by LILO. This is ually only used if the system uses hardware the kernel is having a difficult time auto-detecting. |
|
|
Vga |
Specifies the VGA text mode that should be used while the system is booting. |
|
|
Initrd |
Specifies the initial ramdisk image to be loaded with the kernel. |
|
|
Root |
Specifies the device that should be mounted as root. |
You must type lilo in
the command prompt after making changes.
Grub Bootloader (
Grand Unified Bootloader)
Grub is separated in chunks called stages. These include the following:
Like LILO, it's also
possible to install Stage 1 in the boot partition. In addition, there may
actually be a GRUB stage 1.5 on some deployments. Stage 1 can either load Stage
2 directly, or it may point to stage 1.5, which resides in the first 30kb after
the MBR of the hard disk. Stage 1.5 then loads Stage 2.
To initially install grub you would enter grub-install device. The device would be the device whose MBR you want to install stage 1 into. Example: grub-install /dev/had
Grub references disks differently then LILO. The following is GRUB:
Hddrive_number,partition_number
GRUB Configuration File Option:
|
Section |
Option |
Description |
|
Global |
Color |
Specifies the colors to be used in the GRUB menu. |
|
|
Default |
Specifies the menu item that will be booted automatically if the user doesn't make a manual selection. |
|
|
Timeout |
Specifies the number of seconds to wait until the default menu item is automatically booted. |
|
|
Gfxmenu |
Specifies the location of the image file that will be used to display the graphical GRUB boot menu. |
|
Title |
Title |
Specifies the title of the menu item in the GRUB boot menu. |
|
|
Root |
Specifies the location of the partition that is to be mounted as the GRUB root. |
|
|
Kernel |
Specifies the location of the Linux kernel. |
|
|
Initrd |
Specifies the initrd image that should be used by GRUB to create the initial ramdisk image during boot. |
Runlevels
|
Runlevel |
Description |
|
0 |
Halts the system |
|
1 |
Runs Linux in single-user mode. The command-line interface is used. |
|
2 |
Runs Linux in multi-user mode with networking disabled. The command-line interface is used. |
|
3 |
Runs Linux in multi-user mode with networking enabled. The command-line interface is used. |
|
4 |
Unused |
|
5 |
Runs Linux in multi-user mode with networking enabled. The graphical user interface is used. |
|
6 |
Reboot |
The syntax for
commands within the inittab file is identifier:runlevel:action:command. The wait action specified in these commands tells the init process to
wait until the scripts for the specified runlevel have finished running before
moving on.
[ init completes the following tasks as it initializes a BSD-type system ]
[ init completes the following taks on a V-type system ]
Important Files in
/etc/init.d
|
File |
Init Style |
Function |
|
Rc |
BSD and System V |
This script is used to switch between runlevels while the system is running. |
|
Halt |
BSD |
This script can stop or reboot your system. It is run if the current runlevel is changed to 0 or 6. |
|
Boot |
BSD |
This script is run by init when the system first starts. It runs the scripts contained in /etc/init.d/boot.d. These scripts accomplish a variety of startup tasks, such as loading kernel modules, verifying the file systems, and setting the system clock. |
|
Boot.local |
BSD |
This script is also run by init at startup. It contains additional startup commands. This script is extremely useful. If you want to run a particular command automatically at startup, you can insert the command into this file with a text editor. |
|
Rc.sysinit |
System V |
This script's function is similar to the boot script on a BSD-type system. It's used to set the path, check the file system for errors, set the system clock, etc. |
|
Rc.local |
System V |
This script's function is similar to that of the boot.local script on a BSD-type system. You can add your own commands to this script to ensure they are run every time the system boots. |
You can change runlevels by typing init runlevel example: init 3
If you look inside an
rcx.d directory within your distribution's init directory, you will see two
scripts for each system process. One starts with an "S" and one starts with a
"K". The scripts that start with S are used to start a process while the
scripts that start with "K" are used to kill a process. These are the scripts
employed when switching between runlevels on the fly as just described.
chkconfig - updates and queries runlevel information for system services
SYNOPSIS
chkconfig --list [name]
chkconfig --add name
chkconfig --
chkconfig [--level levels] name <on|off|reset>
chkconfig [--level levels] name
Bash Configuration
File
Type of Shell
Function
~/.bashrc
Non-login shells (Although login shells on most distributions read this file as well. It is usually called from one of the configuration files listed below.
Stores individual user's shell preferences.
/etc/profile
Login shells
Contains configuration parameters that are applied system-wide
~/.bash_profile
Login shells
Stores individual users' shell preferences
~/.bash_login
Login shells
Stores individual users' shell preferences
~/.profile
Login shells
Stores individual users' shell preferences
~/bash_logout
Login shells
Specifies actions to be performed when a user logs out from the shell.
Commonly Used
Environment Variables
|
Environment
Variable |
Stores |
Default Values |
|
BASH and SHELL |
The full path to the shell executable |
/bin/bash |
|
CPU |
The type of CPU installed in the system |
Depends on your system. An Intel Pentium IV computer would have a value of i686. |
|
DISPLAY |
The location where your X Windows display should be sent |
0.0 (the local video card and monitor) |
|
ENV |
The name of the file bash read to configure its environment |
~/.bashrc |
|
EUID |
The user ID (UID) of the current user |
The UID number of the current user |
|
HISTFILE |
The path to the bash command history file |
~/.bash_history |
|
HISTSIZE |
The number of commands saved in the command history |
1000 |
|
HOME |
The path to the current user's home directory |
The current user's home directory. |
|
HOST and HOSTNAME |
The hostname of the system |
The hostname you assigned when you installed the system |
|
INFODIR |
The path to your system's info program |
/usr/local/info:/usr/share/info:/usr/info |
|
LOGNAME |
The username of the current user |
The username of the current user |
|
|
The path to the current user's mailbox file |
/var/spool/mail/username |
|
MANPATH |
The path to your system's man program |
/usr/local/man:/usr/share/man:/usr/X11R6/man:/opt/gnome/share/man |
|
OLDPWD |
The path to the prior current directory |
Depends on what your prior current directory was |
|
OSTYPE |
The type of operating system currently running |
Linux |
|
PATH |
A list of directories to be searched when running a command from the shell prompt |
Depends on your distribution |
|
PS1 |
The characters used to create the shell prompt |
Depends on your distribution |
|
PWD |
The path to the current working directory |
Depends on what your current directory is |
You can use the set command to view all your variables in a linux system. You can also use the env command to see your system environment variables.
You must type export VARIABLE to use a new or changes variable on a new shell.
File descriptors:
Stdin - This file descriptor stands for standard input. Standard input is the input provided to a particular command to process. The stdin for a command is represented by the number 0.
Stdout - This file descriptor stands for standard output. Standard output is simply the output from a particular command. For example, the directory listing generated by the ls command is its stdout. The stdout for a command is represented by the number 1.
Stderr - This file descriptor stands for standard error. Standard error is the error code generated, if any, by a command. The stderr for a command is represented by the number 2.
Cat file > output - will save stdout ( no errors )
Cat file 1> output - will save stdout ( no errors )
Cat file 2> output - will save stderr ( ERRORS )
Cat file 1> output 2>&1 - This will put both stdout and stderr in the same file.
Cat file 1>> output 2>&1 - This will output both stdout and stderr to the same file.
Sed Commands
s - Replaces instances of a specified text string with another text string. The syntax for using the s command is sed s/term1/term2/.
d - Deletes the specified text. For example, to delete every line of text from the stdin that contains the term "eos", you would enter sed /eos/d.
AWK character outputs
\t - Inserts a tab character
\n - Adds a new line character.
\f - Adds a formfeed character.
\r - Adds a carrieage return character.
Shell Scripts
All variables are interpreted as text unless defined otherwise. To declare a variable to be an integer use the following code: declare -i VAR.
If/Then/Else
statement structure:
If condition then
Commands
Else
Commands
Fi
Check if a directory/file exists.
If [ -e $VAR ]; then
Echo "exists";
Fi
Case Syntax
Case variable in
Response_1 ) commands
;;
Response_2 ) commands
;;
Response_3 ) commands
;;
Esac
Example:
Read NAME
Case $NAME in
Tully ) echo "Your name is Tully!"
;;
Tullyr ) echo "Awesome Tullyr!"
;;
Rankin ) echo "You have my last name!"
;;
* ) echo "Your name is not cool"
;;
Esace
Exit0
While Loops
While condition
Do
Script commands
Done
Until loop
Until condition
Do
Script commands
Done