Thursday, February 28, 2013

How to Count no. of files/directory in a directory

Steps are mentioned in snapshot , To count no of files/directory in a directory
> go to directory (here DistSys) in which you have to find no. of files and folders
>now run ls command and pipe it's output to command " wc -l "

cd DistSys
ls | wc -l

which gives a number say 11 ,which means directory DistSys contains 11 files or folders.

Thursday, February 21, 2013

How to create your own command in linux

If you want to add your own command in linux operating system then

write any script.for example i want to add command which displays present

working directory with list of files or folders under it.then type following in gedit or any editor


echo "present directory is `pwd` "

echo "files are `ls` "

save it with any name say pwdfiles

now make it executable

chmod +x pwdfiles

now copy it to /usr/bin directory.

cp pwdfiles /usr/bin/

Sunday, February 17, 2013

How to set Default Boot Option to Windows OS or Vista

To set Default Boot option to any operating system say xyz you need to edit grub.cfg file
which resides under /boot/grub directory.
boot screen will look like this...

and each options are numbered from 0 to n( 7 here )

Ubuntu,with linux 2.6.35-23-generic =0
Ubuntu,with linux 2.6.35-23-generic(recovery mode)=1
Ubuntu,with linux 2.6.35-22-generic =2
Ubuntu,with linux 2.6.35-22-generic(recovery mode)=3
Memory test (memtest86+) =4
Memory test(memtest86+,serial console 115200) =5
Windows Vista (loader) (on /dev/sda1) =6
Windows Vista (loader) (on /dev/sda2) =7

now in grub.cfg file set default="7" to keep default boot windows vista
and to keep ubuntu as default boot
set default="0"

Wednesday, February 13, 2013

Installation Error, “Unable to lock the administration directory”

Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable)
this error occurs during installation of software when lock file is being modified
by some other process or when you are trying to install two different software at
the same time so get rid of this problem
1>install one software at a time

but the problem still persist then

run the following command

rm /var/lib/dpkg/lock

this command removes lock over lock file.location of the file may be different in
different linux operating system

How to install packages in ubuntu

Before you install any package in ubuntu you need to run three commands
1> sudo dpkg --configure -a
2> sudo apt-get update
3> sudo apt-get upgrade
you have to execute these commands in sequence.after executing these commands
go to synaptic software center in ubuntu and select any package which you want to install.

How to set path in ubuntu

To set path for new program you just need to edit .profile or .bash_profile file
which is present in /etc . for example if you want to set path for program xyz
which is present in /usr then export PATH=":/usr/xyz"

don't forget to put ":" before /usr/xyz otherwise it will overwrite the path variable
and path variable will no longer have it's original values.

Monday, February 11, 2013

Could not connect to session bus

"could not connect to session bus: //bin/dbus-launch terminated abnormally without any error message"

if you get error message like this on ubuntu it means value of PATH variable has changed and hence it's not able to run /usr/bin/dbus-launch . On the login screen Press CTRL+ALT+F1, then type in your regular name and password. and run export PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games" now restart system and then after login set path variable .profile file.

Sunday, February 10, 2013

SU:Authentication Failure

            when you install ubuntu and run su command first time it will show the message authentication you need to set super user password by running the following command.
$ sudo passwd
then it will ask for new password and then confirm password.
after this u can run su command.