Create user in mysql

The mysql user information is kept inside USER table under mysql database. So creation of new user will affect the USER table of mysql database. In order to know a list of mysql users according with user table’s description issue,

Here test is the root account password.

mysql -u root -ptest
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 5
Server version: 5.1.30-community MySQL Community Server (GPL)

Type ‘help;’ or ‘\h’ for help. Type ‘\c’ to clear the buffer.

mysql> use mysql;
Database changed

mysql> desc user;
+-----------------------+-----------------------------------+------+-----+---------+-------+
| Field                 | Type                              | Null | Key | Default | Extra |
+-----------------------+-----------------------------------+------+-----+---------+-------+
| Host                  | char(60)                          | NO   | PRI |         |       |
| User                  | char(16)                          | NO   | PRI |         |       |
| Password              | char(41)                          | NO   |     |         |       |
| Select_priv           | enum('N','Y')                     | NO   |     | N       |       |
| Insert_priv           | enum('N','Y')                     | NO   |     | N       |       |
| Update_priv           | enum('N','Y')                     | NO   |     | N       |       |
| Delete_priv           | enum('N','Y')                     | NO   |     | N       |       |
| Create_priv           | enum('N','Y')                     | NO   |     | N       |       |
| Drop_priv             | enum('N','Y')                     | NO   |     | N       |       |
| Reload_priv           | enum('N','Y')                     | NO   |     | N       |       |
| Shutdown_priv         | enum('N','Y')                     | NO   |     | N       |       |
| Process_priv          | enum('N','Y')                     | NO   |     | N       |       |
| File_priv             | enum('N','Y')                     | NO   |     | N       |       |
| Grant_priv            | enum('N','Y')                     | NO   |     | N       |       |
| References_priv       | enum('N','Y')                     | NO   |     | N       |       |
| Index_priv            | enum('N','Y')                     | NO   |     | N       |       |
| Alter_priv            | enum('N','Y')                     | NO   |     | N       |       |
| Show_db_priv          | enum('N','Y')                     | NO   |     | N       |       |
| Super_priv            | enum('N','Y')                     | NO   |     | N       |       |
| Create_tmp_table_priv | enum('N','Y')                     | NO   |     | N       |       |
| Lock_tables_priv      | enum('N','Y')                     | NO   |     | N       |       |
| Execute_priv          | enum('N','Y')                     | NO   |     | N       |       |
| Repl_slave_priv       | enum('N','Y')                     | NO   |     | N       |       |
| Repl_client_priv      | enum('N','Y')                     | NO   |     | N       |       |
| Create_view_priv      | enum('N','Y')                     | NO   |     | N       |       |
| Show_view_priv        | enum('N','Y')                     | NO   |     | N       |       |
| Create_routine_priv   | enum('N','Y')                     | NO   |     | N       |       |
| Alter_routine_priv    | enum('N','Y')                     | NO   |     | N       |       |
| Create_user_priv      | enum('N','Y')                     | NO   |     | N       |       |
| Event_priv            | enum('N','Y')                     | NO   |     | N       |       |
| Trigger_priv          | enum('N','Y')                     | NO   |     | N       |       |
| ssl_type              | enum('','ANY','X509','SPECIFIED') | NO   |     |         |       |
| ssl_cipher            | blob                              | NO   |     | NULL    |       |
| x509_issuer           | blob                              | NO   |     | NULL    |       |
| x509_subject          | blob                              | NO   |     | NULL    |       |
| max_questions         | int(11) unsigned                  | NO   |     | 0       |       |
| max_updates           | int(11) unsigned                  | NO   |     | 0       |       |
| max_connections       | int(11) unsigned                  | NO   |     | 0       |       |
| max_user_connections  | int(11) unsigned                  | NO   |     | 0       |       |
+-----------------------+-----------------------------------+------+-----+---------+-------+
39 rows in set (0.14 sec)
mysql> select host, user from user;
+-----------+---------+
| host      | user    |
+-----------+---------+
| %         | magento |
| 127.0.0.1 | root    |
| localhost |         |
| localhost | magento |
| localhost | pma     |
| localhost | root    |
+-----------+---------+
6 rows in set (0.00 sec)

By query the Insert_priv, Update_priv, Delete_priv, Create_priv, Drop_priv, Reload_priv, Shutdown_priv, Process_priv etc you can check whether user has certain types of privilege or not.

There are several ways to create user in mysql which is described below.

Way 01: With the CREATE USER statement
1)Connect to mysql database as a user who must have the global CREATE USER privilege or the INSERT privilege for the mysql database. You can use root because by default root has privilege to create user.

2)In fact CREATE USER statement creates a new record in the mysql.user table that has no privileges assigned by default.

mysql> create user arju;
Query OK, 0 rows affected (0.13 sec)

mysql> select  user,password, host, select_priv, insert_priv from mysql.user where user='arju';
+------+----------+------+-------------+-------------+
| user | password | host | select_priv | insert_priv |
+------+----------+------+-------------+-------------+
| arju |          | %    | N           | N           |
+------+----------+------+-------------+-------------+
1 row in set (0.00 sec)

Notice that if you specify only the user name part of the account name while creating user, a host name part of ‘%’ is used.

User arju is not assigned any password in this way as you see password is null. To assign password to user arju issue,

mysql> set password for ‘arju’=password(‘test’);
Query OK, 0 rows affected (0.03 sec)

mysql> select  user,password, host, select_priv, insert_priv from mysql.user where user='arju';
+------+-------------------------------------------+------+-------------+-------------+
| user | password                                  | host | select_priv | insert_priv |
+------+-------------------------------------------+------+-------------+-------------+
| arju | *94BDCEBE19083CE2A1F959FD02F964C7AF4CFC29 | %    | N           | N           |
+------+-------------------------------------------+------+-------------+-------------+
1 row in set (0.00 sec)

In one command you can set password while creating user. The following command will crate a user arju2 and password is test in the host localhost. Both password, username and hostname should be within single quote.

mysql> create user ‘arju2’@’localhost’ identified by ‘test’;
Query OK, 0 rows affected (0.00 sec)

mysql> select  user,password, host, select_priv, insert_priv from mysql.user where user='arju2';
+-------+-------------------------------------------+-----------+-------------+-------------+
| user  | password                                  | host      | select_priv | insert_priv |
+-------+-------------------------------------------+-----------+-------------+-------------+
| arju2 | *94BDCEBE19083CE2A1F959FD02F964C7AF4CFC29 | localhost | N           | N           |
+-------+-------------------------------------------+-----------+-------------+-------------+
1 row in set (0.00 sec)

If you don’t put username, host name and password within single quote syntax error will be resulted.

mysql> create user ‘arju2’@’localhost’ identified by test;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ‘test’ at line 1

An equivalent statement of setting password is issuing update statement.

mysql> UPDATE mysql.user SET Password=PASSWORD(‘test’)
-> WHERE User=’arju’ AND Host=’%’;

Query OK, 0 rows affected (0.05 sec)
Rows matched: 1 Changed: 0 Warnings: 0

Changing via update and insert of the user table, it is necessary to use FLUSH PRIVILEGES to tell the server to reload the grant tables. Otherwise, the changes go unnoticed until you restart the server.

mysql> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.08 sec)

mysql> select  user,password, host, select_priv, insert_priv from mysql.user where user='arju';
+------+-------------------------------------------+------+-------------+-------------+
| user | password                                  | host | select_priv | insert_priv |
+------+-------------------------------------------+------+-------------+-------------+
| arju | *94BDCEBE19083CE2A1F959FD02F964C7AF4CFC29 | %    | N           | N           |
+------+-------------------------------------------+------+-------------+-------------+
1 row in set (0.00 sec)

Now, have a look that connecting to mysql database as user arju will fail but arju2 will be successful.
D:\xampp\mysql\bin>mysql -u arju -ptest
ERROR 1045 (28000): Access denied for user ‘arju’@’localhost’ (using password: YES)

D:\xampp\mysql\bin>mysql -u arju2 -ptest
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 18
Server version: 5.1.30-community MySQL Community Server (GPL)

Type ‘help;’ or ‘\h’ for help. Type ‘\c’ to clear the buffer.

mysql> select user();
+-----------------+
| user()          |
+-----------------+
| arju2@localhost |
+-----------------+
1 row in set (0.00 sec)

Note that the ‘arju’@’localhost’ account can be used only when connecting from the local host. The ‘arju’@’%’ account uses the ‘%’ wildcard for the host part, so it can be used to connect from any host.

You can check the privilege assigned for a user by issuing,

mysql> show grants for arju;
+-----------------------------------------------------------------------------------------------------+
| Grants for arju@%                                                                                   |
+-----------------------------------------------------------------------------------------------------+
| GRANT USAGE ON *.* TO 'arju'@'%' IDENTIFIED BY PASSWORD '*94BDCEBE19083CE2A1F959FD02F964C7AF4CFC29' |
+-----------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql> show grants for arju2;
ERROR 1141 (42000): There is no such grant defined for user 'arju2' on host '%'
mysql> show grants for arju2@localhost;
+--------------------------------------------------------------------------------------------------------------+
| Grants for arju2@localhost                                                                                   |
+--------------------------------------------------------------------------------------------------------------+
| GRANT USAGE ON *.* TO 'arju2'@'localhost' IDENTIFIED BY PASSWORD '*94BDCEBE19083CE2A1F959FD02F964C7AF4CFC29' |
+--------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

By default it is search for host ‘%’.

Way 02: With the grant option
To create a user named momin with password test2 and all privileges for a particular database called ecommerce issue,
mysql> grant ALL PRIVILEGES on ecommerce.* to ‘momin’@’localhost’ identified by ‘test2’;
Query OK, 0 rows affected (0.00 sec)

mysql> use mysql;
Database changed

mysql> select host, user from user where user='momin';
+-----------+-------+
| host      | user  |
+-----------+-------+
| localhost | momin |
+-----------+-------+
1 row in set (0.00 sec)

D:\xampp\mysql\bin>mysql -u momin -ptest2
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 32
Server version: 5.1.30-community MySQL Community Server (GPL)

Type ‘help;’ or ‘\h’ for help. Type ‘\c’ to clear the buffer.

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| ecommerce          |
| test               |
+--------------------+
3 rows in set (0.00 sec)

Here ecommerce database is shown as we have given permission.

Way 03: Using INSERT statement into Table mysql.user
You can also create user in mysql by simply INSERT a new row into mysql.user table. Note that creating user through INSERT statement needs to use FLUSH PRIVILEGES to tell the server to reload the grant tables. If we don’t do that the changes go unnoticed until you restart the server. This restriction is not applicable in CREATE USER statement.
Insert statement can be issued in two ways. One way to create user robert,

mysql> use mysql;
Database changed

mysql> INSERT INTO user SET Host=’localhost’,User=’robert’, Password=password(‘test’);
Query OK, 1 row affected, 3 warnings (0.00 sec)

Alternative way of creating user richard is,

mysql> INSERT INTO user (Host,User,Password)
-> VALUES(‘localhost’,’richard’,password(‘test’));

Query OK, 1 row affected, 3 warnings (0.00 sec)

mysql> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.00 sec)

Check by,

mysql> select user, host, password from user where user in('robert','richard');
+---------+-----------+-------------------------------------------+
| user    | host      | password                                  |
+---------+-----------+-------------------------------------------+
| robert  | localhost | *94BDCEBE19083CE2A1F959FD02F964C7AF4CFC29 |
| richard | localhost | *94BDCEBE19083CE2A1F959FD02F964C7AF4CFC29 |
+---------+-----------+-------------------------------------------+
2 rows in set (0.01 sec)

See that while setting password we used the PASSWORD() function with INSERT in order to encrypt the password. But with the CREATE USER statement it was unnecessary as create user statement automatically encrypts the password.

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How to Fix Cpanel/WHM quota

To Fix Common reasons for quota problems

Run the following command as root user.

/scripts/fixquotas

Try finding other files owned by the user.

find -user username > /tmp/username.txt

This will list all files owned by this user that could be affecting the quota reported by Cpanel.

Cpanel/WHM sometimes has problems with the user quota files causing all users accounts to have unlimited disk space available or 0 megs of disk space in use.

*To enable user quota support on a file system, add “usrquota” to the fourth field containing the word “defaults”.

If you need both user quota and group quota support on a file system?, then edit /etc/fstab

...
/dev/hda2 /home ext3 defaults,usrquota,grpquota 1 1

touch /partition/aquota.user

chmod 600 /partition/aquota.user

Re-boot or re-mount file partition with quotas.

From the Linux Man Pages:

quotacheck – scan a filesystem for disk usage, create, check and repair quota files.

quotacheck -vgum /partition
or
quotacheck -vguma

-v, –verbose
quotacheck reports its operation as it progresses.  Normally it operates silently.  If the option is  specified  twice,  also the current directory is printed (note that printing can slow down the scan measurably).

-u, –user
Only user quotas listed in /etc/mtab or on the filesystems specified are to be checked.  This is the default action.

-g, –group
Only group quotas listed in /etc/mtab or on the filesystems specified are to be checked.

-m, –no-remount
Don’t try to remount filesystem read-only. See comment with option -M.

-a, –all
Check all mounted non-NFS filesystems in /etc/mtab

NOTE
quotacheck should only be run by super-user. Non-privileged users are presumably not allowed to read  all  the  directories  on  the  given filesystem.

FILES

aquota.user or aquota.group :  located at filesystem root with quotas (version 2 quota, non-XFS filesystems)

quota.user or quota.group :located at filesystem root with quotas (version 1 quota, non-XFS filesystems)
/etc/mtab      names and locations of mounted filesystems


Example Steps for /home partition:

1. First check whether quota is enabled for /home partition.

# vi /etc/fstab

LABEL=/home /home ext3 defaults,usrquota 1 2

2. Remount the /home partition

# mount -o remount /home

3. Create a file called aquota.user for which we need to run quotacheck.

# quotacheck -c /home

4. Enable quota

# quotaon /home

This will enable quota on /home. Now you can edit the quota of a user using.

# edquota <username>

5) Run /scripts/fixquotas this will solve the quota issue of cpanel accounts.

# /scripts/fixquotas

6) After this `repquota -a` should print out the soft/hard limits with grace periods for all users. If quotas are still not reporting anything in WHM and/or CPanel, check

# repquota -a

7) /var/cpanel/cpanel.config for disablequotacache=0

If that is set to 0, try setting it to 1 and see if that fixes it.

# vi /var/cpanel/cpanel.config ; /scripts/fixquotas

8) If a user’s quota shows more space being used than is in their home directory chances are there are stray files on the system owned by their UID. To find these files, run the following as root:

# find -user username > /tmp/username.txt

Hope this helps.

Mod_Rewrite – Hide index.php

This article follows Mod_Rewrite and .htaccess which explains how an .htaccess file can be used to prevent search engines from indexing non-www web pages that contain exactly the same content as those with-www in front. By hiding the ‘duplicate content’ we avoid the risk of a ‘downgrading’ effect by Google and other search engines.

Exactly the same principle applies to web page addresses like:

http://www.mysite.com/index.php
http://www.mysite.com/subfolder/index.php

when we want the content to be displayed only on:

http://www.mysite.com/
http://www.mysite.com/subfolder/

This can be done by using ModRewrite to permanently redirect (eg):

http://www.mysite.com/index.php
to
http://www.mysite.com/

The file index.php continues to exist on the website but there’s no need for ‘index.php’ to appear in the page address for its content to be displayed. The same applies to ‘index.html’, ‘default.html’ (etc) and to ‘index’ pages located in sub-folders, eg ‘/subfolder/index.php’ or ‘/subfolder/another/index.php’. Those filenames should never normally be displayed to the visitor. The process of hiding them is sometimes referred to as the canonicalization of index pages.
The .htaccess file

For websites running on Apache web server (most websites do), a Mod_Rewrite module can be enabled to allow an .htaccess file to be installed in the root folder, containing rules on how web page requests should be rewritten ‘behind the scenes’ by the ‘rewriting engine’. The Mod_Rewrite rules to achieve the effect we want here are:

#
Options +FollowSymLinks
RewriteEngine On
#
# REDIRECT /folder/index.php to /folder/
RewriteCond %{THE_REQUEST}
(on same line) ^[A-Z]{3,9}\ /([^/]+/)*index\.php\ HTTP/
RewriteRule ^(([^/]+/)*)index\.php$
(on same line) http://www.mysite.com/$1 [R=301,L]
#

Piece by piece…

A line beginning with hash (#) is ignored by the web server and is useful to split up the rules visually, and to add comments.

Options +FollowSymLinks
RewriteEngine On

For the rewriting engine to work, we need to enable Options FollowSymLinks and set RewriteEngine On (this is for security).

# REDIRECT /folder/index.php to /folder/
RewriteCond %{THE_REQUEST}
(on same line) ^[A-Z]{3,9}\ /([^/]+/)*index\.php\ HTTP/
RewriteRule ^(([^/]+/)*)index\.php$
(on same line) http://www.mysite.com/$1 [R=301,L]

The .htaccess file is eliminating the duplicate content problem by redirecting the visitor (and Google) from all the site’s web page addresses that contain the superfluous index.php to the folder name (directory) in which they reside. Exactly the same content is presented as if the index.php file itself was being viewed, but index.php doesn’t appear in the browser’s address bar.
How the Mod_Rewrite works

(1) RewriteCond

Looking first at RewriteCond, we need to specify the conditions under which the RewriteRule will be processed by the server, and here, we want our rule to apply to any ‘index.php’ page requested on the domain. This prevents the .htaccess file from triggering an ‘infinite loop’ on the server, in which the RewriteRule keeps repeating itself. If the request contains ‘index.php’ (as in the condition we’ve referenced), it has not yet been rewritten. If it has been rewritten, it won’t contain ‘index.php’ and the RewriteRule won’t be applied.

%{THE_REQUEST}

In this part, {THE_REQUEST}, is a standard server variable, in this instance the page requested by the visitor, because that’s what we’re going to try to match in the second part. In RewriteCond, a server variable is preceded by $ to denote an Apache variable.

^[A-Z]{3,9}\ /([^/]+/)*index\.php\ HTTP/

This second part is known as the ‘condition’. The ^ caret defines the start, and is followed by a regular expression. Looking at the regular expression in detail:

[A-Z]{3,9}\ matches from 3 to 9 occurences of any uppercase letter (eg ‘GET’) followed by an \ escaped space.

/([^/]+/)* matches a forward slash followed by any quantity of [one or more characters not preceded by a forward slash but ending with a forward slash], eg ‘/subfolder1/subfolder2/’.

index\.php\ matches ‘index.php’ – the backslashes are required to ‘escape’ (i) the dot metacharacter (to make it into a real dot) and (ii) the space before ‘HTTP/’.

HTTP/ matches ‘HTTP/’.

Why do we need all this? Because we’re testing our condition against {THE_REQUEST} – the entire client request header for an ‘index’ page, which is typically something like:

GET /index.php HTTP/1.1
or
GET /subfolder1/index.php HTTP/1.1

(2) RewriteRule

Looking now at the RewriteRule, it contains three essential parts.

^(([^/]+/)*)index\.php$

This first part is the ‘thing’ that we want to be re-written by the web server. The ^ caret symbol defines the start, (([^/]+/)*) is a designated variable (using brackets) containing a regular expression that matches a forward slash followed by any quantity of [one or more characters not preceded by a forward slash but ending with a forward slash], eg ‘/subfolder1/subfolder2/’, index\.php matches ‘index.php’, and the $ symbol defines the end.

http://www.mysite.com/$1

This second part is what we want the server to process behind the scenes. It consists of the domain’s root folder (homepage) plus the designated variable from the first part, expressed as $1.

In the above example, the designated variable (([^/]+/)*) is added by the server, after the page has been requested, as $1 to the end of http://www.mysite.com/. If the requested ‘index’ page is the site’s homepage, the $1 variable will be empty and the server will simply process http://www.mysite.com/. If the requested ‘index’ page is in a subfolder and the designated variable’s value is ‘/folder1/’, the server will process http://www.mysite.com/folder1/.

[R=301,L]

This third part, the flag, designates any special instructions that might be needed, in this instance R=301 for redirect permanently and L for ‘last rule’ so that no other rules are processed for the specified rewrite condition.

The full rewrite rule is thus:

RewriteRule ^(([^/]+/)*)index\.php$
(on same line) http://www.mysite.com/$1 [R=301,L]

The RewriteRule in action

Here, again, is the full .htaccess file:

#
Options +FollowSymLinks
RewriteEngine On
#
# REDIRECT /folder/index.php to /folder/
RewriteCond %{THE_REQUEST}
(on same line) ^[A-Z]{3,9}\ /([^/]+/)*index\.php\ HTTP/
RewriteRule ^(([^/]+/)*)index\.php$
(on same line) http://www.mysite.com/$1 [R=301,L]
#

In plain English, it’s saying that “if someone tries to open a folder’s ‘index.php’ page, redirect them to a version of the folder without ‘index.php’, and if the visitor is Google(bot), mention the fact that this is permanent.”

See this in action by typing http://www.patricktaylor.com/index.php into an HTTP viewer. The first receiving header is HTTP/1.1 301 Moved Permanently and the second receiving header is HTTP/1.1 200 OK. And of course it can be tested by attempting to view http://www.patricktaylor.com/index.php in your browser.

Mod_Rewrite and .htaccess

Grabbing code snippets off the web and re-using them on one’s own websites is easy enough to do. Every web designer solves a problem this way at one time or another. Having done so, why not take a little trouble to understand what the code is doing? This article looks at a simple example of a code snippet and attempts to demystify some of the so-called voodoo surrounding rewriting URLs with .htaccess.

Mod_Rewrite is an Apache web server module that is often installed on shared web hosting packages. If the module is available, a special file named .htaccess can be uploaded to the server, containing rules on how web page requests should be handled ‘behind the scenes’ by the ‘rewriting engine’. The .htaccess file is normally placed in a website’s root folder to apply its effect to all pages on the domain.
Why have an .htaccess file?

An .htaccess file is important to any webmaster who is interested in a good ranking in search engines, especially Google. It has many uses, the most basic being to prevent search engines from indexing different pages (URLs) that contain exactly the same content.
A simple .htaccess example: the canonical URL

Consider two web pages:

http://www.mysite.com/
http://mysite.com/

Technically, these two URLs are different pages, but they contain exactly the same content when viewed. If Google indexes both, there’s a risk that one, or the other, or both, will be ‘downgraded’ by Google as ‘duplicate content’. With the .htaccess file, this can be prevented by nominating only one as the ‘canonical’ homepage. Here’s an example of what to put in the file:

#
Options +FollowSymLinks
RewriteEngine On
#
# REDIRECT to canonical url
RewriteCond %{HTTP_HOST} ^mysite\.com [NC]
RewriteRule ^(.*)$ http://www.mysite.com/$1 [R=301,L]
#

Piece by piece…

A line beginning with hash (#) is ignored by the web server and is useful to split up the rules visually, and to add comments.

Options +FollowSymLinks
RewriteEngine On

For the rewriting engine to work, we need to enable Options FollowSymLinks and set RewriteEngine On (this is for security).

# REDIRECT to canonical url
RewriteCond %{HTTP_HOST} ^mysite\.com [NC]
RewriteRule ^(.*)$ http://www.mysite.com/$1 [R=301,L]

The ‘canonical URL’ is the preferred internet address for a web page, and in the above instance is any page at http://www.mysite.com/. The .htaccess file is removing the duplicate content problem by redirecting the visitor (and Google) from the non-www version to the with-www version. This means that only canonical URLs will ever be accessible – for all the pages on the domain, not just the homepage.
How the Mod_Rewrite works

(1) RewriteCond

Looking firstly at RewriteCond, we need to specify the conditions under which the RewriteRule will be processed by the server, and here, we want our rule to apply only when a visitor (or Google) attempts to view http://mysite.com/any-page (without www).

%{HTTP_HOST}

In this first part, {HTTP_HOST}, is a standard server variable, in this instance the site’s host (domain name), because that’s what we’re going to try to match in the second part. In RewriteCond, a server variable is preceded by $ to denote an Apache variable.

^mysite\.com

This second part is known as the ‘condition’. The ^ caret symbol defines the start and mysite\.com is the pattern to be matched, in this instance http://mysite.com without www. The backslash before the dot is required to ‘escape’ it, because in a regular expression, the dot is a special ‘metacharacter’. Escaping the dot converts it back to a normal character – a plain dot.

[NC]

This third part is known as the flag. [NC] stands for no case (case-insensitive).

The full rewrite condition is thus:

RewriteCond %{HTTP_HOST} ^mysite\.com [NC]

(2) RewriteRule

Looking now at the RewriteRule, it contains three essential parts.

^(.*)$

This first part is the ‘thing’ that we want to be re-written by the web server. The ^ caret symbol defines the start, (.*) is a designated variable (using brackets) containing a regular expression that matches any combination of characters, and the $ symbol defines the end.

http://www.mysite.com/$1

This second part is what we want the server to process behind the scenes. It consists of the canonical URL, plus the designated variable from the first part, expressed as $1. If we had two designated variables we could use $1 and $2.

In the above example, the (.*) (any combination of characters, eg: ‘about-us.html’) is added by the server, after the page has been requested, as $1 to the end of http://www.mysite.com/ to make http://www.mysite.com/about-us.html.

[R=301,L]

This third part, the flag, is an integral part of the rule writing process because it designates any special instructions that might be needed, in this instance R=301 for redirect permanently and L for ‘last rule’ so that no other rules are processed for the specified rewrite condition.

The full rewrite rule is thus:

RewriteRule ^(.*)$ http://www.mysite.com/$1 [R=301,L]

The RewriteRule in action

Here, again, is the full .htaccess file:

#
Options +FollowSymLinks
RewriteEngine On
#
# REDIRECT to canonical url
RewriteCond %{HTTP_HOST} ^mysite\.com [NC]
RewriteRule ^(.*)$ http://www.mysite.com/$1 [R=301,L]
#

In plain English, it’s saying that “if someone tries to open any page on our website without entering www at the front, redirect them to a version of the page with the www, and if the visitor is Google(bot), mention the fact that this is permanent.”

The redirect can be tested by typing a web page address like http://patricktaylor.com/mod_rewrite-htaccess into an HTTP viewer. The first receiving header is HTTP/1.1 301 Moved Permanently and the second receiving header is HTTP/1.1 200 OK. And of course the addition of www can be tested by pasting http://patricktaylor.com/ into your browser’s address bar.

A general note: on some shared web hosting accounts, the .htaccess file can’t be seen when the root folder is opened in an FTP client. This can often be corrected by enabling server side filtering in the FTP client program and setting the remote filter as -rtaF. The precise details of how to do this will vary from one program to another.

The tee command

Note this command, very useful one

Command : tee

About tee:

** Read from an input and write to a standard output or file.

Eg: ls *.txt | wc -l | tee /dev/tty count.txt

Sample O/P

nazeem@111:~$ ls *.txt | wc -l | tee /dev/tty count.txt
7
7
nazeem@111:~$

** ls command would list all .txt files in the current directory, take a word count and the output displayed to the /dev/tty (terminal) will be sent to the count.txt.

** One of the important use of tee was that it can use  see intermediate out put of each portion in complex commands and also you can generate intermediate log file using tee command.

Eg:

nazeem@111:~$ ls *.txt |tee count.txt | wc -l
7
nazeem@111:~$ cat count.txt
a.txt
count.txt
load.txt
ls.txt
m.txt
server.txt
test.txt
nazeem@111:~$

Here the intermediate o/p was written to the file count.txt

** You can also print the intermediate o/p on terminal via

nazeem@111:~$ ls *.txt |tee /dev/tty | wc -l
a.txt
count.txt
load.txt
ls.txt
m.txt
server.txt
test.txt
7
nazeem@111:~$

Script For DNS forwarding of all accounts under a RESELLER Account

updateResellerDNS.sh

Written By Nazeem S
Copy the bellow content and put it in file called “updateResellerDNS.sh” and give permission 755(executable) then run it (sh updateResellerDNS.sh or ./updateResellerDNS.sh)

############# Starting ########################
###############NAZEEM S####################
#############################################
#! /bin/bash
>/var/log/updateResellerDNS.log
>user
>domains
echo -n “Enter Reseller Account Name:— ”
read a
echo -n “Enter IP to be Changed (Source IP):— ”
read b
echo -n “Enter the New IP (Destination IP):— ”
read c
grep $a /etc/trueuserowners |cut -d ‘:’ -f1|sort >user

for i in `cat user`
do
cat /etc/userdomains|grep $i |cut -d: -f1|sort >>domains;
done
for x in `cat domains`
do
ls /var/named/ |grep $x|sort >>updateResellerDNS.log;
done
for y in `cat updateResellerDNS.log`
do
#replace ‘$b’ ‘$c’ –/var/named/$y;
sed -i ‘s/$b/$c/g’ /var/named/$y;
echo “$y—————- converted”
done
export c=`cat updateResellerDNS.log | wc -l`
echo “Total count of zone files has been updated = $c”
echo “log file on /var/log/updateResellerDNS.log”
#############################################
###############NAZEEM S####################
############### Ending #######################