BusyBox v1.18.5 (Ubuntu 1:1.18.5-1ubuntu4) built-in shell (ash) Enter 'help' for a list of built-in commands. (initramfs)

1. Boot from Ubuntu Alternate

As ext3 and ext4 are quite robust, it should be repaired quite easily with a tool like fsck run from a live CD. The main constraint is that the live CD should allow not to mount the root filesystem of the host computer.
After a quick search, I realised that Ubuntu Alternate allows to do that.
So, first step is to download Ubuntu Precise PC (Intel x86) alternate install CD and to :

• either write the ISO file to a CD-ROM
• or generate a USB key with unetbootin or startup disk boot creator under Ubuntu

Next step is to boot from your CD-ROM or USB Key on your computer with a corrupted filesystem.
From the main menu, select the last choice Rescue a broken system.

After selecting your keyboard, follow all the steps till the Filesystem Mount menu.
Select the last menu Do not use root file system.
Next, select the menu Execute a shell in the installer environment.
You will get a busybox prompt.

2. Repair Corrupted Root Filesystem

From the prompt, type :

# fdisk -l
Périphérique Amorce Début Fin Blocs Id Système
/dev/sda1 * 1 3647 29294496 83 Linux
/dev/sda2 3648 121601 947465505 5 Etendue
/dev/sdb3 120582 121601 8193150 82 Linux swap / Solaris

Here, the root filesystem is the first one : /dev/sda1. It is of Linux type.
To repair it, we just need to run fsck with the force option :

# fsck.ext3 -f /dev/sda1

At the end of the fdisk command, your filesystem should be repaired.
At this stage, you should already be able to succesfully reboot your computer.

3. Search your Hard Disk for Bad Sectors

Please note that this step is not compulsory at all.
In case you feel that your hard disk may be in an unhealty condition, you may want to search for bad sectors.
To search for bad sectors on your hard disk, you can need to run fdisk with the check option.

# fsck.ext3 -c /dev/sda1

This action may take a very long time to complete.

Once you root filesystem has been repaired, you just need to reboot ... and your Ubuntu system should be back to life !

Error when installing rabbitMQ server on centos5.6

Best way is to tell rabbitmq to not to look for hostname.
You can do that using rabbitmq config file.
edit config, create it if it does not exist

vim /etc/rabbitmq/rabbitmq.conf
vim /etc/rabbitmq/rabbitmq-env.conf (in later versions of RabbitMQ)

Add following entries:

NODENAME=rabbit@localhost 
NODE_IP_ADDRESS=127.0.0.1

Remove Control M' Characters (^M) with Unix and Linux commands

Using dos2unix  command
dos2unix ORIG_FILENAME TEMP_FILENAME
mv TEMP_FILENAME ORIG_FILENAME
IMP NOTE: use dos2ux command if you are using HPUX
                    use dos2unix  command if you are using LINUX
Using sed command
sed ‘s/^M//g’ ORIG_FILENAME > TEMP_FILENAME
mv TEMP_FILENAME ORIG_FILENAME
IMP NOTE: To get ^M in UNIX (Hold control key and then press v and m character).  
Using vi Editor
ESCAPE   :%s/^M//g ENTER
IMP NOTE: To get ^M in UNIX (Hold control key and then press v and m character).

EXP-00008: ORACLE error 904 encountered ORA-00904: "IFREEPOOL": invalid identifier

Applies to:

Oracle Server - Enterprise Edition - Version: 10.2.0.3 to 10.2.0.4
This problem can occur on any platform.

Symptoms

Export reports ORA-00904 "IFREEPOOL": invalid identifier while using a version 10.2.0.4.0 export client to export from a 10.2.0.3.0 database.

Export Log File 
--------------- 
. . Export der Tabelle CALCULATEDFIELDS 
EXP-00008: ORACLE-Fehler 904 aufgetreten 
ORA-00904: "IFREEPOOL": invalid identifier 

Cause

This is an expected behaviour.
The version of the Export utility must be equal to the earliest version of the source or target database. Here, the source database is based on release 10.2.0.3.0 and hence the export client has to be a version 10.2.0.3.0.
An export client of a later release cannot be used for the following reasons:

• The export utility is continuously accessing dictionary objects such as SYS.EXU9LOB.
• Starting with release 10.2.0.4.0 we introduced additional columns such as 'IFREEPOOL'. This column is not available in 10.2.0.3.0 and hence the client cannot handle this and ORA-00904/EXP-00008 appears.
  
  Client 10.2.0.4.0 is not supported to export from 10.2.0.3.0 database.

Solution

The version of the Export utility must be equal to the earliest version of the source or target database.

RCS Basics ( Building a Simple Local RCS Repository)

Create a subdirectory named RCS in your private working directory:

$ mkdir RCS

Check in files you want to add to the repository (this moves them into the RCS repository):

$ ci foo.c
$ ci blah.c

Check out file you want to work on (-l locks the file so only you can check it out to modify it):

$ co -l foo.c
$ co -l blah.c

Subsequent check-ins create a new version of the file, and you can revert to older versions by using the -r flag with co (see the man pages for co and ci for more details).
Some other commands (and see man page for rcsintro):

$ rcsdiff foo.c    ( diff between foo.c and latest version in repository)
$ rlog  foo.c      ( see the log messages associated with commits to foo.c)

Run Multiple Apache On Single Host

In this blog post we are going to discuss on how to run two Apache instances on single Linux host.

We already have one Apache installed and serving the static content. The Apache is installed at the following location:

/etc/httpd

Let`s copy the directory /etc/httpd to /etc/avon_httpd

  cp -pr /etc/httpd  /etc/avon_httpd   

Now, as we have copied the old Apache web-server to a new location /etc/avon_httpd. We need to make the changes to the configuration file.

cd  /etc/avon_httpd and open the httpd.conf file in a vi editor and make changes to the following values:

ServerRoot “/etc/httpd”  TO ServerRoot “/etc/avon_httpd”

Listen 80 TO Listen 82

PidFile run/httpd.pid TO PidFile run/avon_httpd.pid

Save and close the file.

In the next step we are going to copy the RHEL httpd configuration file.

 cp -pr /etc/sysconfig/httpd  /etc/sysconfig/avon_httpd 

In the next step, let`s copy the script /etc/init.d/httpd  TO /etc/init.d/avon_httpd

 cp -pr  /etc/init.d/httpd   /etc/init.d/avon_httpd 

In this step, Link the /usr/sbin/httpd TO /usr/sbin/avon_httpd

 ln -s  /usr/sbin/httpd   /usr/sbin/avon_httpd 

Open the file avon_httpd under /etc/sysconfig/ and enter the following lines:

## CUSTOM SETTINGS ##
HTTPD=/usr/sbin/avon_httpd
OPTIONS="-f /etc/avon_httpd/conf/httpd.conf"
LOCKFILE=/var/lock/subsys/avon_httpd
PIDFILE=/var/run/avon_httpd.pid

Open the avon_httpd file under /etc/init.d and replace httpd to avon_httpd.

The command used to start/stop httpd and avon_httpd service could be:

• /etc/init.d/httpd {start|stop|restart|condrestart|reload|status|fullstatus|graceful|help|configtest}
• /etc/init.d/avon_httpd {start|stop|restart|condrestart|reload|status|fullstatus|graceful|help|configtest}

Ubuntu 12.10- No Unity GUI(missing sidebar in ubuntu 12.10)

Install unity Package  first

sudo apt-get install unity

To see what will happen.

For now, it might be easier for you to use some other DE, such as Gnome-shell.

sudo apt-get install gnome-shell

Then restart Your system .