How to delete certain lines of text from a file in Bash using sed

Posted on December 28, 2009 by Ahmed Tawfik

“sed -i 1,+2d file_name”

deletes starting from line ‘1’ and the next ‘2’ lines, i.e. deletes the first 3 lines

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Cleanup the SSH known_hosts file

Posted on December 28, 2009 by Ahmed Tawfik

“ssh-keygen -R [host] “

helpful especially in clusters

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How to randomly change your MAC address on Ubuntu

Posted on December 28, 2009 by Ahmed Tawfik

“sudo apt-get install macchanger”
“sudo macchanger -A eth0”

where “eth0” is the network card you’d like to change its MAC.

Note: You have to edit your connection in Network Manager and change the old MAC with the new one, or – which is much better in my opinion – just remove the MAC from there to be obtained dynamically.

Source

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Change your hostname randomly in Ubuntu

Posted on December 28, 2009 by Ahmed Tawfik

The following script worked great:

#!/bin/bash

#random_computer_name

sudo sed -i 1,10d /etc/hostname

function randnum
{
number=$[ ( $RANDOM % 15 ) + 8 ]
}

randnum

function randpass
{
newhostname=`
}

randpass

(echo ‘0a’; echo $newhostname; echo ‘.’; echo ‘wq’) | sudo ed -s /etc/hostname

sudo /bin/hostname $newhostname

Just add the above script in a file and execute it with “sudo”.

To add this file to your startup scripts, just follow the instructions in this post

Source: here

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Change your computer’s hostname in Ubuntu

Posted on December 28, 2009 by Ahmed Tawfik

“sudo hostname new_name“

where “new_name” is the new hostname you’ll use

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