How to undo git add

git reset FILE

How to delete latest git commit

Assuming you are sitting on that commit, then this command will wack it...

git reset --hard HEAD~1

The HEAD~1 means the commit before head.
Or, you could look at the output of git log, find the commit id of the commit you want to back up to, and then do this:

git reset --hard 

---

If you already pushed it, you will need to do a force push to get rid of it...

git push origin HEAD --force

However, if others may have pulled it, then you would be better off starting a new branch. Because when they pull, it will just merge it into their work, and you will get it pushed back up again.
If you already pushed, it may be better to use git revert, to create a "mirror image" commit that will undo the changes. However, both commits will both be in the log.

---

FYI -- git reset --hard HEAD is great if you want to get rid of WORK IN PROGRESS. It will reset you back to the most recent commit, and erase all the changes in your working tree and index.

---

Lastly, if you need to find a commit that you "deleted", it is typically present in git reflog unless you have garbage collected your repository.

Copyright: http://stackoverflow.com/questions/1338728/how-to-delete-a-git-commit

Creating foreign keys in mysql

Syntax:

[CONSTRAINT [symbol]] FOREIGN KEY
    [index_name] (index_col_name, ...)
    REFERENCES tbl_name (index_col_name,...)
    [ON DELETE reference_option]
    [ON UPDATE reference_option]

Few things to remember:

- set default engine to InnoDB

- the foreign key must have the same column definition with the referencing table column

Example:

CREATE TABLE IF NOT EXISTS `product` (
  `product_id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(100) DEFAULT NULL,
  PRIMARY KEY (`product_id`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 AUTO_INCREMENT=68 ;

CREATE TABLE IF NOT EXISTS `category` (
  `category_id` int(10) NOT NULL AUTO_INCREMENT,
  `name` varchar(200) NOT NULL,
  PRIMARY KEY (`category_id`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 AUTO_INCREMENT=3 ;

CREATE TABLE IF NOT EXISTS `product_category` (
  `product_id` int(10) unsigned NOT NULL,
  `category_id` int(10) NOT NULL,
  FOREIGN KEY (`product_id`) REFERENCES `product` (`product_id`) ON DELETE CASCADE ON UPDATE CASCADE,
  FOREIGN KEY (`category_id`) REFERENCES `category` (`category_id`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

Install Squid on CentOS / RHEL 5

Source: http://www.cyberciti.biz/tips/howto-rhel-centos-fedora-squid-installation-configuration.html

Use yum command as follows:

# yum install squid
Output:

Loading "installonlyn" plugin
Setting up Install Process
Setting up repositories
Reading repository metadata in from local files
Parsing package install arguments
Resolving Dependencies
--> Populating transaction set with selected packages. Please wait.
---> Package squid.i386 7:2.6.STABLE6-4.el5 set to be updated
--> Running transaction check
Dependencies Resolved
=============================================================================
 Package                 Arch       Version          Repository        Size
=============================================================================
Installing:
 squid                   i386       7:2.6.STABLE6-4.el5  updates           1.2 M
Transaction Summary
=============================================================================
Install      1 Package(s)
Update       0 Package(s)
Remove       0 Package(s)
Total download size: 1.2 M
Is this ok [y/N]: y
Downloading Packages:
Running Transaction Test
Finished Transaction Test
Transaction Test Succeeded
Running Transaction
  Installing: squid                        ######################### [1/1]
Installed: squid.i386 7:2.6.STABLE6-4.el5
Complete!

Squid Basic Configuration

Squid configuration file located at /etc/squid/squid.conf. Open file using a text editor:
# vi /etc/squid/squid.conf
At least you need to define ACL (access control list) to work with squid. The defaults port is TCP 3128. Following example ACL allowing access from your local networks 192.168.1.0/24 and 192.168.2.0/24. Make sure you adapt to list your internal IP networks from where browsing should be allowed:
acl our_networks src 192.168.1.0/24 192.168.2.0/24
http_access allow our_networks

Save and close the file. Start squid proxy server:
# chkconfig squid on
# /etc/init.d/squid start
Output:

init_cache_dir /var/spool/squid... Starting squid: .       [  OK  ]

Verify port 3128 is open:
# netstat -tulpn | grep 3128
Output:

tcp        0      0 0.0.0.0:3128                0.0.0.0:*                   LISTEN      20653/(squid)

Open TCP port 3128

Finally make sure iptables is allowing to access squid proxy server. Just open /etc/sysconfig/iptables file:
# vi /etc/sysconfig/iptables
Append configuration:
-A RH-Firewall-1-INPUT -m state --state NEW,ESTABLISHED,RELATED -m tcp -p tcp --dport 3128 -j ACCEPT
Restart iptables based firewall:
# /etc/init.d/iptables restart
Output:

Flushing firewall rules:                                   [  OK  ]
Setting chains to policy ACCEPT: filter                    [  OK  ]
Unloading iptables modules:                                [  OK  ]
Applying iptables firewall rules:                          [  OK  ]
Loading additional iptables modules: ip_conntrack_netbios_n[  OK  ]

Client configuration

Open a webbrowser > Tools > Internet option > Network settings > and setup Squid server IP address and port # 3128.

Create pdf on the fly

http://www.fpdf.org/

How to edit git commit message

git commit --amend -m "edited message here"