Redhat / CEntOS / Oracle Linux, Tips and Tricks

How to Delete all files except a Pattern in Unix

Good Morning To All My TECH Ghettos,

Today ima show ya’ll a fuckin command to delete all files except a pattern,

ya’ll can use it in a script or even commandline ……. Life gets easy as Fuck !!!!!!!!

find . -type f ! -name ‘<pattern>’ -delete

A Live Example



After the following Command

find . -type f ! -name ‘*.gz’ -delete


Operating System, Redhat / CEntOS / Oracle Linux, Tips and Tricks

Error :- sudo: effective uid is not 0, is sudo installed setuid root?

We all as a Linux administrator must have come across this error sometime in our lives.

[user@host dir]$ sudo bash
sudo: effective uid is not 0, is sudo installed setuid root?

This happens when sudo does not get the right access permissions.

The Solution for this error is giving the following permissions as root user

chmod u+s /usr/bin/sudo

That Must Sort the issue for CentOS Kind of distros.


Main, Redhat / CEntOS / Oracle Linux, Tips and Tricks, Ubuntu

Safest and the least vulnerable way to add a user to the sudoers with full rights


demouser ALL=(ALL) PASSWD:ALL, !/bin/su root, !/bin/su -, !/bin/sudo su -, !/bin/su – root, !/bin/sudo su root, !/bin/su, !/usr/bin/passwd, !/usr/bin/passwd root, !/bin/vi /etc/sudoers, !/usr/bin/sudo vi /etc/sudoers, !/usr/sbin/visudo, !/usr/sbin/sudo visudo, !/bin/chmod 777 /etc/sudoers, !/bin/chmod ugo+rwx /etc/sudoers



Tips and Tricks

How to Send Email from Telnet

We use the “” as an example.

Be sure to replace with your own domain.

Open your command prompt.

Now, connect with telnet using the following command:

telnet 25

Some servers also accept helo in place of ehlo.


Type mail

mail from:
rcpt to:,,

To write the message – type data, followed by your subject and message. To end the message, put a period on a line by itself and press enter:

Subject: My Telnet Test Email


This is an email sent by using the telnet command.

Your friend,



Type quit to exit telnet.

Open your command prompt.
At the command prompt, type in

telnet 110

Type user and the email address ( of the user for which you wish to view emails:


Then type in pass followed by your password:

pass yourpasswordgoeshere

Type list to bring up a list of your emails:
You will see a list of items with labels like “1 897” and “2 5136.” Here is an example:
+OK POP3 clients that break here, they violate STD53.

1 897
2 5136
3 1884
4 2973
5 2595
6 3063
7 3509
8 2283
9 1926
10 2763
11 1795
12 2780
13 2342
14 2342
15 2342
16 3833
17 2211
18 793
19 797
20 2599

If you wish to read an email message such as 2 5136, you can type the following:

retr 2

If you want to delete a message such as 1 897, type dele 1:

dele 1

When you are done checking your email, type quit.



Telnet on Wikipedia