Friday, 26 September 2014

How to disable your browser's popup blockers

The following includes steps for disabling pop-up window blockers.
  • Internet Explorer 7 (WindowsXP)
  • Internet Explorer6 (Windows XP)
  • Firefox (Windows PC)
  • Firefox (Mac OSX)
  • Mozilla (Mac OSX)
  • Safari (MacOSX)
The following includes steps for disabling Brower toolbars.
  • Yahoo toolbar popup blocker
  • Google toolbar popup blocker
  • AOL toolbar popup blocker
  • MSN toolbar popup blocker
  • Norton Internet Security/Personal Firewall popup blocker

How to disable Internet Explorer 7 popup blocker (Windows XP)

  1. From the Tools menu, select Internet Options.

  2. Windows
  3. From the Privacy tab, uncheck Turn on Pop-up Blocker and click "OK".

  4. Windows

How to disable Internet Explorer 6 popup blocker (Windows XP)

  1. From the Tools menu, select Internet Options.


 From the Privacy tab, uncheck Block pop-ups

How to disable the Firefox popup blocker (Windows PC)

  1. From the Tools menu, select Options.
  2. From the Content tab, uncheck Block Popup Windows and click "OK".


How to disable the Firefox popup blocker (Mac OSX)

  1. From the Firefox menu, select Preferences.
  2. From the Preferences window, choose the Content button and then uncheck Block Pop-up Windows.

  3. firefox

How to disable the Mozilla popup blocker (Mac OSX)

  1. From the Mozilla menu, select Preferences.
  2. From the Privacy & Security tab, choose Popup Windows. Un-check Block unrequested popup windows, and click "OK"

How to disable the Safari popup blocker

  1. From the Safari menu, make sure Block Pop-Up Windows is unchecked.
  2. Choose Safari > Preferences, and then click Security.
  3. Turn on “Block pop-up windows.”


How to disable the Yahoo toolbar popup blocker

  1. Locate the Popup blocker icon and click the down arrow.

  2. Uncheck Enable Pop-Up Blocker.


How to disable the Google toolbar popup blocker?

  1. Click on the Google logo on the Google toolbar and select Options.
  2. Uncheck Popup Blocker, and then click OK.

How to disable AOL toolbar popup blocker?

  1. Locate the Popup blocker icon.
    msn and aol
  2. Click on it until it says Allowed.
    msn and aol

How to disable the MSN toolbar popup blocker?

  1. Locate the Popup blocker icon and click the down arrow.
    msn and aol
  2. Check Allow Pop-ups.
    msn and aol

How do I disable my Norton Internet Security/Personal Firewall popup blocker?

  1. Open Norton Internet Security's/Firewall�s main window (you may click the firewall icon on the system tray or use Start->Programs->Norton Firewall)
  2. Click the Ad Blocking line.
  3. Click the Turn Off button.


Saturday, 6 September 2014

Give FTP User access to specific directory in Linux

To create FTP user through SSH you would need to follow below mentioned steps:

1. Login as root through SSH.

2. Next add the user account you want using the 'useradd' command

useradd <username>

3. Now create a special group for that user.

groupadd <groupname>

4. Now to add the user to the group

gpasswd -a <username> <groupname>

These commands are non-standard but available on most popular distributions. If not, then you can
try editing /etc/group using your favorite text editor.

5. Change the group ownership of the special directory to that group.

chgrp -Ra groupname

6. Enable write permissions

chmod -R g+rw


How to give ftp users access to directories outside their home folder in Linux

Say you have 2 users, with 2 different websites:
User sonu:
  • Home folder:  /home/sonu
  • Document root, virtual-host: /var/www/
User sujeet:
  • Home folder: /home/sujeet
  • Document root, virtualhost: /var/www/
And you are using vsftpd, with the setting chroot_local_user=YES so that users are limited to their own home folder.

You could create a link ( ln -s ) between /home/sujeet/ and /var/www/ so sujeet could manage his website from his home directory. that would work, but not via ftp, since it does not follow links outside sujeet’s home folder.


Instead of using the traditional link, you can in Linux mount two folders like this:
Make sure the directories /home/sujeet/ and /var/www/ exists (create them with mkdir)
Then mount the two folders with mount –bind  /home/sujeet/ /var/www/
Now Alex should be able to update his website files in his home folder, via ftp, and at the same time, Apache can serve his website from the default /var/www directory (ubuntu default).


This is a simpler workaround, a solution, but not to the specific problem of giving ftp users access.
Instead of linking or mounting directories between Apaches www folder and users home folder, you could just point the document root of the Apache virtual-hosts to /home/sujeet/ or /home/sonu/ instead.



Tuesday, 2 September 2014

ORA-01555 snapshot too old

What is "snapshot too old" error and how to avoid it?

First thing to be understood here is how rollback segments work. These work in a circular fashion by looping around to reuse the extents which have been released by committed transactions. Thus in case of long running queries if data is changed while the query is running, rollback segments created for that change are needed to make a read consistent image for the lon running query. When these extents are reused while these were still need by the query, this error occurs, because oracle can no longer provide a read consistent image of the data.
To avoid this error you need to postpone the reuse of extents. Thus increasing the size of rollback segments and the value of OPTIMAL parameter should do the trick. Committing less often would be other solution. As until transaction is c omitted rollback segment can not be reused thus reducing the chances of a snapshot too old error.

You'll probably need to dive into Oracle DB administration if you want to solve it via increasing the UNDO log. Basically you do (as SYSDBA):
SQL> show parameter undo

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
undo_management                      string      AUTO
undo_retention                       integer     900
undo_tablespace                      string      APPS_UNDOTS1

21600 is 6 hours in seconds.
However, Oracle will only keep 6 hours of old data if the UNDO log files are big enough, which depends on the size of the rollback segments and the amount of updates executed on the database.
So in addition to changing the undo retention time, you should also make sure that few concurrent updates are executed while your job is running. In particular, updates of the data your job is reading should be minimized.
If everything fails, increase the UNDO logs.