Tip / Trick for web developers

Today I was trying to install JEvent2.0 in Joomla1.5.23 for one of my client.
But, when ever I "upload and install" JEvent I was getting few MySQL error messages.
Something like this:
* Component Install: DB function failed with error number 2006
MySQL server has gone away SQL=INSERT INTO ULJoomla_components VALUES( 0, 'JEvents MVC', 'option=com_jevents', 0, 0, 'option=com_jevents', 'JEvents MVC', 'com_jevents', 0, 'js/ThemeOffice/component.png', 0, '', 1 )
SQL =

INSERT INTO ULJoomla_components VALUES( 0, 'JEvents MVC', 'option=com_jevents', 0, 0, 'option=com_jevents', 'JEvents MVC', 'com_jevents', 0, 'js/ThemeOffice/component.png', 0, '', 1 )

* Error Loading ModulesMySQL server has gone away SQL=SELECT id, title, module, position, content, showtitle, control, params FROM ULJoomla_modules AS m LEFT JOIN ULJoomla_modules_menu AS mm ON mm.moduleid = m.id WHERE m.published = 1 AND m.access <= 2 AND m.client_id = 1 ORDER BY position, ordering

Solution:
Extract the archive file and paste the complete path and press "Install" (not upload and install).
But, in my case I don't have full path since I have access to joomla's root directory using ftp only.
Here, goes the solution, how I made it worked for me:
1. upload the archive file into (joomla'root directory)/tmp/
2. now use "upload and install" method to install file.
Finally installed smoothly without a single issue.

Alias to find process id of a running process

This is an example for those who believe in saving time.
You can create your own aliases to save your time from typing long commands again and again.
Create alias
# alias p_id='echo -n '\''process name:'\'';read a;ps -e | grep firefox | cut -d '\'' '\'' -f 2'
Execute it
# p_id
process name:[name of the running process]
[output will be the process id]

[Alpha version] Now it is simple to install rpm packages on other pc which don't have internet connection.

Run this script package-script.sh from the system which has internet connection then copy the package.tar.gz file.

Now,
How to install packages on other pc which don't have internet connection.
1. paste package.tar.gz into non-internet pc.
2. Switch to root user using
$ su -
3. Extract tarball
# tar -C packagepkd -xvf package.tar.gz
4.
# cd packagepkd/.package/
5. rpm -ivh ....
check "man rpm" for more details.

Note:
Kindly, report here if you find any bug.

How to remove all *.lnk files from pen drive

Yesterday, I have connected my pen drive on someone else's system. Now, when I return home and connected my pen drive on my system, I have found lnk files for each file and directory in my pendrive. It is a waste of time deleting those files one by one. So, here is a simple command to remove all lnk files.

# find /path/to/pendrive -name '*.lnk' -exec rm -v '{}' ';'

How to change MAC address in fedora

1. First step is to find the current MAC address and take a backup copy in a safe place.

To know your current MAC type:
$ ifconfig | grep HWaddr
eth0 Link encap:Ethernet HWaddr 00:19:48:2E:D1:27

The above hexadecimal numbers 00:19:48:2E:D1:27 is your MAC address for device eth0.
Simply copy and paste it in a file.

2. Now, time to change the MAC address this requires you to work as root user.
Take the network interface down
# ifdown eth0

Now, lets change the current MAC address to 00:E0:81:5C:B4:0F
# ifconfig eth0 hw ether 00:E0:81:5C:B4:0F

Take the network interface up again
# ifconfig eth0 up

Check if your MAC address is changed:
# ifconfig eth0 | grep HWaddr

Note:
Changing MAC address is only temporary. Once you reboot your machine, the operating system will reflect the physical MAC address burnt in your network card and not the MAC address you set.

Default Permission

Default Permission:
For Normal Users:-
1. On File:
-rw-rw-r-- or 664
2. On Directory:
drwxrwxr-x or 775

For users with root permissions:-
1. On File:
-rw-r--r-- or 644
2. On Directory:
drwxr-xr-x or 655

File and Directory Permissions

File Permissions:
1. -r--
content of the file can be read using command such as cat, less or more.
2. -rw-
Note: read permission is required to write into any file.
file can be edited and saved
3. -r-x
Note: read permission is required to execute any file.
shell (bash or sh, etc) will attempt to execute the file when file's name is entered as a command.

Directory Permissions:
1. dr--
content of directory can be read as ls.
Few examples:
$ ls testing/
ls: cannot access testing/file2: Permission denied
ls: cannot access testing/file1: Permission denied
file1 file2

Note: long listing requires execute permission.
Few examples:
$ ll testing/
ls: cannot access testing/file2: Permission denied
ls: cannot access testing/file1: Permission denied
total 0
-????????? ? ? ? ? ? file1
-????????? ? ? ? ? ? file2

2. d-wx
files may be created or delected in the directory.
Note:
a). execute permission required.
b). A file can be deleted by anyone who has write permission to directory in which the file resides regardless of the ownership or permission for that file.
Few examples:
a). $ ls testing/ [Failed]
ls: cannot open directory .: Permission denied

3. d--x
enter into directory using command cd
Few examples:
a). $ ls testing/
ls: cannot open directory testing/: Permission denied
b). $ cd testing/ [Okay]