Happy Holi

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systemd – start service when you enable it

More often than not for any service, I end up doing :

systemctl enable <service>
systemctl start <service>

But there is shorcut to this. In systemctl command when you enable the service, you can use “–now” to start the service as follows:

systemctl enable --now <service>

quite a timesaver 🙂

Linux Best Practices and Tips

<p>
  Have you ever typed a command in your terminal, only to find out you forgot to prefix it with the
</p>

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          1<br />
        </div>
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      <td>
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          sudo
        </div>
      </td>
    </tr>
  </table>
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<p>
  command? You have to retype the whole command again just to add the
</p>

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          1<br />
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          sudo
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      </td>
    </tr>
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<p>
  in front of it. Frustrating!
</p>

<p>
  Well, you can add this simple alias to your
</p>

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          1<br />
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          .bashrc
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    </tr>
  </table>
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<p>
  to help you reduce the frustration:
</p>

<pre>

  <td>
    <div class="text codecolorer">
      alias argh='sudo $(history -p \!\!)'
    </div>
  </td>
</tr>

Kernel dropped packet analysis

Found a simple method to check for all the packets dropped by kernel.

First you need to install dropwatch with

dnf install dropwatch

and details of the package

Name        : dropwatch

Arch        : x86_64

Epoch       : 0

Version     : 1.4

Release     : 13.fc24

Size        : 27 k

Repo        : fedora

Summary     : Kernel dropped packet monitor

URL         : http://fedorahosted.org/dropwatch

License     : GPLv2+

Description : dropwatch is an utility to interface to the kernel to monitor for dropped

network packets.

bash ansi codes to html for html reports from shell script

How many times you have felt that there was some simple way to convert bash ansi escape sequences ( colors as well in terminal ) to html equivalent so that you can send the same as html report in email. Here is simple solution. One way is to use ccze if you are using this for logs – colorize your logs and for more generic solution.

dnf install python3-ansi2html.noarch

after this is installed, you can use something like this:

Get kernel function name from kernel address.

If you are using pmap or using strace and want to covert kernel address to function name then you can use the following technique.

First you need to install elfutils, if not installed.

dnf install elfutils

and after this you can use the following command

eu-addr2line -f -e /boot/vmlinuz-$(uname -r) <addr>
#Example
eu-addr2line -f -e /boot/vmlinuz-$(uname -r) 00007f36a8045000

Mehandi

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