Change your MAC address in Linux (Ubuntu)

Relevant to your use, you can either choose to make it a permanent addition or a temporary addition. Lets take an example of changing the MAC address of interface eth0 to 11:22:33:44:44:66

Temporary Addition

$ sudo ifconfig eth0 down

$ sudo ifconfig eth0 hw ether 11:22:33:44:55:66

$ sudo ifconfig eth0 up

Permanent Addition

1. Open /etc/network/interfaces ,

$ sudo vim /etc/network/interfaces

2. Add an extra line to specify the new MAC

auto eth0

iface eth0 inet dhcp

hwaddress ether 01:02:03:04:05:06

(A simple configuration, additional configurations will require additions/alterations. E.g. static IP/different interface)

3. Restart the network service

$ /etc/init.d/networking restart

Though the the latest version of Ubuntu may require you to use the service command to start/stop/restart services

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Search your history of commands

I just recently discovered that one can search a history of commands(in BASH) in  a few keystrokes , rather than the ancient way of pressing the up arrow till you see it or eventually doze off 🙂

Press Ctrl + R

Start typing the command u want to search for( it starts autocompleting)

Once you reach the right command -> Type Enter

Happy Searching 🙂

scp – Copy from/to remote server with SSH

scp stands for secure cp (copy), which means that you can copy files across an ssh connection that will be encrypted, and therefore secured.

You can this way copy files from or to a remote server, you can even copy files from one remote server to another remote server.

Usage

scp [[user@]from-host:]source-file [[user@]to-host:][destination-file]

Description of options

from-host
Is the name or IP of the host where the source file is, this can be omitted if the from-host is the host where you are actually issuing the command
user
Is the user which have the right to access the file and directory that is supposed to be copied in the cas of the from-host and the user who has the rights to write in the to-host
source-file
Is the file or files that are going to be copied to the destination host, it can be a directory but in that case you need to specify the -r option to copy the contents of the directory
destination-file
Is the name that the copied file is going to take in the to-host, if none is given all copied files are going to maintain its names

Options

-p
Preserves the modification and access times, as well as the permissions of the source-file in the destination-file
-q
Do not display the progress bar
-r
Recursive, so it copies the contents of the source-file (directory in this case) recursively
-v
Displays debugging messages

Examples

scp *.txt user@remote.server.com:/home/user/

This will copy all files with .txt extension to the directory /home/user in the remote.server.com host

scp -r miguel@10.1.2.2:/home/miguel/ miguel@10.1.2.3:/home/miguel/

This is going to recursively copy all files from miguel’s Home directory on 10.1.2.2 host to his Home directory in 10.1.2.3 host.

Note

To use this command you need to have open-ssh installed in the hosts.

Installing .deb packages through the shell

dpkg is a tool to install, build, remove and manage packages. dpkg itself is controlled entirely via command line parameters

To install package called package.deb type the following command:

Go to directory where package.deb is kept. For example if it is in /tmp directory:

$ cd /tmp

Type the following command:

$ sudo dpkg -i package.deb

Unix tar command

About tar

Create tape archives and add or extract files.

Examples

Note: A “.tar” file is not a compressed files, it is actually a collection of files within a single file uncompressed. If the file is a .tar.gz (“tarball“) or “.tgz” file it is a collection of files that is compressed. If you are looking to compress a file you would create the tar file then gzip the file.

Creating a tar file:

tar -cvvf file.tar myfile.txt

In the above example the system would create a tar named file.tar in the directory you currently are in. Wildcards could also be used in this command, for example: tar -cvvf file.tar *.txt would compress all txt files in the current directory.

tar -cvvf home.tar home/

In the above example command the system would create a tar file named home.tar in the directory you currently are in of the home directory.

Extracting the files from a tar file:

tar -xvvf myfile.tar

In the above example command the system would uncompress (untar) the myfile.tar file in the current directory.

tar -xvvzf myfile.tar.gz

In the above example command the system would uncompress (untar) the myfile.tar.gz file in the current directory.

Note: There is no “untar” linux / unix command.

Creating a tarred file that is compressed with bzip

tar -cjvf test.tbz home/

Adding the j option to the tar command enables tar to compress files and/or directories using bzip. In the above example the home directory and all its subdirectories are added to the compressed test.tbz file.