NOTE: connecting to ‘IP address’: IP address:24800
WARNING: failed to connect to server: No route to host
Problem occurred on the client side while trying connect to server.
The reason for the error was static IP address on the client machine. Thus, the server was not reachable from this end.
The client couldn’t even ping the server.
Changing IP obtaining type to DHCP fixed the issue.
By default on a fresh Debian 6 installation gnome root login is disabled.
To enable the account follow the steps:
- Launch the terminal.
- Open the file
/etc/pam.d/gdm3 with super user privileges
- Comment out the fifth line:
auth required pam_succeed_if.so user != root quiet_success
auth requisite pam_nologin.so
auth required pam_env.so readenv=1
auth required pam_env.so readenv=1 envfile=/etc/default/locale
#auth required pam_succeed_if.so user != root quiet_success
auth optional pam_gnome_keyring.so
session required pam_limits.so
session optional pam_gnome_keyring.so auto_start
- Save the file and reboot the system
Login as root enabled.
I have a Lenovo W520 laptop(graphic cards:intel and nvidia Quadro200M) with centOS 6.3 on it.
Recently, I have encountered an interesting issue I have updated the operating system using yum update command as a regular user with root privileges.
And after reboot, I logged in as the same user but everything was upside down though the screen wasn’t rotated as you can see on the photo. I couldn’t perform any activity because once I logged in, the system froze thus in order to log out I had to user “ctrl + alt + backspace” combination. I was also trying to revert to an old kernel version as it would be a logic explanation, that maybe the update failed but the issue persisted.
Luckily my root account was untouched and was able to create a new regular user and investigate further without the system reinstall.
However, I was not happy with the whole situation and had opened many threads during the investigation period unfortunately, no help from there either.
On some Saturday evening I decided to reinstall the Nvidia driver because wanted to test if the official drivers allow me to connect an external screen to my laptop.
download the latest drivers from here http://www.nvidia.com/Download/index.aspx?lang=en-us
make sure that your system is up to date by launching the command
Then, I found an interesting note saying that I must recompile my driver every time I update a kernel so, I decided to give it a try and hoping to kill two birds with one stone. Here are the steps:
yum update if neccesary restart the machine
install the following packages:
yum install kernel-devel kernel headers gcc make
make sure that you are running the latest kernel
uname -r; rpm -q kernel-devel
blacklist nouveau by editing menu.lst
kernel /boot/vmlinuz rdblacklist=nouveau
verify that your system does not use the aforementioned driver: /sbin/lsmod | grep nouveau
switch to runlevel 3:
use the root account to log in and change the drivers to executable mode:
chmod +x .run
run the driver
./.run and once completed return to level 5
If you can see the login window that is great otherwise carry on with tutorial:
use other OS or liveCD to get access to /etc/X11 folder
remove this file: xorg.conf and restart the machine
This should fix the problem.
In order to use commands listed on this page enter virsh management user interface by executing:
#to connect to local KVM hypervisor
#to list running domains
#to list all domains
#to view the details of a particular virtual machine in xml format
//order in which to contact DNS servers (Domain Name Servers only)
//order in which to contact the name resolvers when a process demands resolving of a host name
//A list of machines that can be contacted using the network, but without the need for a domain name service
dd – cut/delete a line
yy – copy a line
p – paste text
o – create a new line below the cursor
O – create a new line above the cursor
w – save the file
wq – save the file and quit
x – save the and quit
q – quit the file
q! – quit the file disregarding any changes
//search whatis database for strings
//the same as above
man -k keyword
//displays only the manuals whose names begin with the keyword
//search the exact manual name
man -f keyword
//shows the full path of (shell) commands
//to find the alias of a command
//display environment variables
Viewing File Properties
//to find out more about a file type use
Manipulating files and directories
//to create a directory
//to create nested directories(subdirectories)
mkdir -p directory/subdir1/subdir2
//to move files
mv src_file dest_place
//to rename a file
mv file_name new_file_name
//to copy a file
cp src_file dest_place
//to copy directories(recursively)
cp -R src_dir dest_dir
//to remove a file
//to remove an empty directory
//to remove a non-empty directory
rm -r dir_name
//to ask user for confirmation
rm -i file_name
//check an smb.conf configuration file for internal correctness
//displays full database instance name:
select * from global_name;
//displays a sid(instance) name
select sys_context('userenv','instance_name') from dual;
//name of a logged user
select user from dual;
//name of a current instance
select instance from v$thread;
//name of a current instance
select name from v$database;
1. Ensure that environment variables are set so that you connect to the desired Oracle instance:
2. Start oracle instance without connecting to it
3. Connect to database as sysdba
connect username/password as sysdba