Want to urgently copy a text message from one pc to another, or have a short conversation with a peer on another pc ? here’s how –
@ PC1: nc -l [port-number to listen, without brackets of course]
@PC2: nc [IP of PC1] [port-number above]
Now type any text on pc2 – it should be visible on pc1, and vice versa.
Run the following queries –
SET GLOBAL log_output = 'TABLE';SET GLOBAL general_log = 'ON';After the latest 100 queries executed after this is done can be found by running the query –
SELECT * FROM mysql.general_log where argument like ‘%[queryPiece]%’ order by event_time desc LIMIT 0,100
ssh -i [path to private-key-file] [target IP]
# In the host shell
sudo adduser [username] # Add a new user; this command also prompts for setting the password
sudo adduser admin # Add this user to the admin group (to sudoers)
sudo vi /etc/ssh/sshd_config
# In the above file set "PasswordAuthentication" to "yes".
sudo reload sshThe VM should now be ready for password based ssh authentication.
Extract the .gz file to standard output (option -c) and pipe this to target file.
# example
<pre><code>gzip -c inputfile.gz > outputfile</code></pre>On console, run
dpkg -L [package name]To find the list of installed packages on ubuntu/debian, on console run
<pre>dpkg --get-selections</pre>To find if a specific package is installed –
<pre>dpkg --get-selections|grep <packagename></pre>To enable password based authentication on RHEL/Centos machines, login as root to the target host. ( sudo the commands below if you are not logging in as root)
1. Create the password authenticated user if not already created –
2. Add the user to sudoers and enable remote login –
3. Enable password authentication for SSH.
4. To disable password authentication after use, in the above file replace “PasswordAuthentication yes” with “PasswordAuthentication no“; reload sshd as before.
Problem: SSH asks for password even after updating the .ssh/authorized_keys in target host with user’s public key.
Reason: A permission issue
Fix: Login with password, in console run
chmod -R 700 ~Log out and try again. The public key login should work now.
Problem: The arrow keys insert characters, no status message at the bottom etc.
Reason : The default Vim on Ubuntu is vim-tiny, a skeleton version.
Fix: Install the real stuff – sudo apt-get install vim
Note: vi = Visual, vim = Visual improved. And vim-tiny is vi compatible, kind of Jurassic.
Install JDK on Ubuntu manually without depending on PPAs –
sudo update-alternatives --install "/usr/bin/java" "java" "/usr/lib/jvm/jdk1.6.0_32/bin/java" 1
sudo update-alternatives --install "/usr/bin/javac" "javac" "/usr/lib/jvm/jdk1.6.0_32/bin/javac" 1
sudo update-alternatives --install "/usr/bin/javaws" "javaws" "/usr/lib/jvm/jdk1.6.0_32/bin/javaws" 1sudo update-alternatives --config java
sudo update-alternatives --config javac
sudo update-alternatives --config javawsRun java -version to verify installation. Cheers!