Difference between revisions of "Ubuntu OS"

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</pre>
</pre>
== Linux User management ==


=== Add A New User To Secondary Group===
<pre> useradd Example -
You need to the useradd command to add new users to existing group (or create a new group and then add user). If group does not exist, create it. The syntax is as follows:
useradd -G {group-name} username
</pre>
=== Add a new user to primary group ===
<pre>
useradd example -
To add a user tony to group developers use following command:
# useradd -g developers tony
# id tony
</pre>
=== Addding a group ===
<pre># groupadd developers
</pre>
=== Add user called vivek to group developers: ===
<pre>
# useradd -G developers vivek
</pre>
=== Setup password for user vivek: ===
<pre>
# passwd vivek</pre>
''' Please note that capital G (-G) option add user to a list of supplementary groups. Each group is separated from the next by a comma, with no intervening whitespace. For example, add user jerry to groups admins, ftp, www, and developers, enter: '''
<pre>
# useradd -G admins,ftp,www,developers jerry</pre>
''' Please note that small -g option add user to initial login group (primary group). The group name must exist. A group number must refer to an already existing group. '''
=== Add a existing user to existing group ===
<pre>
usermod example -
Add existing user tony to ftp supplementary/secondary group with usermod command using -a option ~ i.e. add the user to the supplemental group(s). Use only with -G option :
# usermod -a -G ftp tony
</pre>
=== Change existing user tony primary group to www: ===
<pre># usermod -g www tony</pre>
=== list all users in a group: ===
<pre> compgen -u</pre>
=== List all groups: ===
<pre> compgen -g</pre>
=== See what groups a user belongs to: ===
<pre>groups nameofuser</pre>
<p>command to Show all users:<br /> cat /etc/passwd <br /> lastlog</p>
<table border="1" rules="ROWS">
<tr>
<td>ac</td>
<td width="10"> </td>
<td>Print statistics about users' connect time.</td>
</tr>
<tr>
<td>accton</td>
<td width="10"> </td>
<td>Turn on accounting of processes. To turn it on type "accton /var/log/pacct".</td>
</tr>
<tr>
<td><strong>adduser</strong></td>
<td width="10"> </td>
<td>Ex: adduser mark - Effect: Adds a user to the system named mark</td>
</tr>
<tr>
<td>chage</td>
<td width="10"> </td>
<td>Used to change the time the user's password will expire.</td>
</tr>
<tr>
<td>chfn</td>
<td width="10"> </td>
<td>Change the user full name field finger information</td>
</tr>
<tr>
<td>chgrp</td>
<td width="10"> </td>
<td>Changes the group ownership of files.</td>
</tr>
<tr>
<td>chown</td>
<td width="10"> </td>
<td>Change the owner of file(s ) to another user.</td>
</tr>
<tr>
<td>chpasswd</td>
<td width="10"> </td>
<td>Update password file in batch.</td>
</tr>
<tr>
<td>chroot</td>
<td width="10"> </td>
<td>Run command or interactive shell with special root directory.</td>
</tr>
<tr>
<td>chsh</td>
<td width="10"> </td>
<td>Change the login shell.</td>
</tr>
<tr>
<td>edquota</td>
<td width="10"> </td>
<td>Used to edit user or group quotas. This program uses the vi editor to edit the quota.user and quota.group files. If the environment variable EDITOR is set to emacs, the emacs editor will be used. Type "export EDITOR=emacs" to set that variable.</td>
</tr>
<tr>
<td>faillog</td>
<td width="10"> </td>
<td>Examine faillog and set login failure limits.</td>
</tr>
<tr>
<td>finger</td>
<td width="10"> </td>
<td>See what users are running on a system.</td>
</tr>
<tr>
<td>gpasswd</td>
<td width="10"> </td>
<td>Administer the /etc/group file.</td>
</tr>
<tr>
<td><strong>groupadd</strong></td>
<td width="10"> </td>
<td>Create a new group.</td>
</tr>
<tr>
<td>grpck</td>
<td width="10"> </td>
<td>Verify the integrity of group files.</td>
</tr>
<tr>
<td>grpconv</td>
<td width="10"> </td>
<td>Creates /etc/gshadow from the file /etc/group which converts to shadow passwords.</td>
</tr>
<tr>
<td>grpunconv</td>
<td width="10"> </td>
<td>Uses the files /etc/passwd and /etc/shadow to create /etc/passwd, then deletes /etc/shadow which converts from shadow passwords.</td>
</tr>
<tr>
<td>groupdel</td>
<td width="10"> </td>
<td>Delete a group.</td>
</tr>
<tr>
<td><strong>groupmod</strong></td>
<td width="10"> </td>
<td>Modify a group.</td>
</tr>
<tr>
<td><strong>groups</strong></td>
<td width="10"> </td>
<td>Print the groups a user is in</td>
</tr>
<tr>
<td><strong>id</strong></td>
<td width="10"> </td>
<td>Print real and effective user id and group ids.</td>
</tr>
<tr>
<td>last</td>
<td width="10"> </td>
<td>Display the last users logged on and how long.</td>
</tr>
<tr>
<td>lastb</td>
<td width="10"> </td>
<td>Shows failed login attempts. This command requires the file /var/log/btmp to exist in order to work. Type "touch /var/log/btmp" to begin logging to this file.</td>
</tr>
<tr>
<td>lastcomm</td>
<td width="10"> </td>
<td>Display information about previous commands in reverse order. Works only if process accounting is on.</td>
</tr>
<tr>
<td>lastlog</td>
<td width="10"> </td>
<td>Formats and prints the contents of the last login.</td>
</tr>
<tr>
<td>logname</td>
<td width="10"> </td>
<td>Print user's login name.</td>
</tr>
<tr>
<td>newgrp</td>
<td width="10"> </td>
<td>Lets a suer log in to a new group.</td>
</tr>
<tr>
<td>newusers</td>
<td width="10"> </td>
<td>Update and create newusers in batch.</td>
</tr>
<tr>
<td><strong>passwd</strong></td>
<td width="10"> </td>
<td>Set a user's pass word.</td>
</tr>
<tr>
<td>pwck</td>
<td width="10"> </td>
<td>Verify integrity of password files.</td>
</tr>
<tr>
<td>pwconv</td>
<td width="10"> </td>
<td>Convert to and from shadow passwords and groups.</td>
</tr>
<tr>
<td>quota</td>
<td width="10"> </td>
<td>Display users' limits and current disk usage.</td>
</tr>
<tr>
<td>quotaoff</td>
<td width="10"> </td>
<td>Turns system quotas off.</td>
</tr>
<tr>
<td>quotaon</td>
<td width="10"> </td>
<td>Turns system quotas on.</td>
</tr>
<tr>
<td>quotacheck</td>
<td width="10"> </td>
<td>Used to check a filesystem for usage, and update the quota.user file.</td>
</tr>
<tr>
<td>repquota</td>
<td width="10"> </td>
<td>Lists a summary of quota information on filesystems.</td>
</tr>
<tr>
<td>sa</td>
<td width="10"> </td>
<td>Generates a summary of information about users' processes that are stored in the /var/log/pacct file.</td>
</tr>
<tr>
<td><strong>smbclient</strong></td>
<td width="10"> </td>
<td>Works similar to an ftp client enabling the user to transfer files to and from a windows based computer.</td>
</tr>
<tr>
<td>smbmount</td>
<td width="10"> </td>
<td>Allows a shared directory on a windows machine to be mounted on the Linux machine.</td>
</tr>
<tr>
<td>smbpasswd</td>
<td width="10"> </td>
<td>Program to change users passwords for samba.</td>
</tr>
<tr>
<td>su</td>
<td width="10"> </td>
<td>Ex: su mark - Effect: changes the user to mark, If not root will need marks password.</td>
</tr>
<tr>
<td>sulogin</td>
<td width="10"> </td>
<td>Single user login.</td>
</tr>
<tr>
<td>ulimit</td>
<td width="10"> </td>
<td>A bash builtin command for setting the processes a user can run.</td>
</tr>
<tr>
<td><strong>useradd</strong></td>
<td width="10"> </td>
<td>Create a new user or update default new user information.</td>
</tr>
<tr>
<td><strong>userdel</strong></td>
<td width="10"> </td>
<td>Delete a user account and related files.</td>
</tr>
<tr>
<td><strong>usermod</strong></td>
<td width="10"> </td>
<td>Modify a user account.</td>
</tr>
<tr>
<td><strong>users</strong></td>
<td width="10"> </td>
<td>Print the user names of users currently logged in.</td>
</tr>
<tr>
<td>utmpdump</td>
<td width="10"> </td>
<td>Used for debugging.</td>
</tr>
<tr>
<td>vigr</td>
<td width="10"> </td>
<td>Edit the password or group files.</td>
</tr>
<tr>
<td>vipw</td>
<td width="10"> </td>
<td>Edit the password or group files.</td>
</tr>
<tr>
<td>w</td>
<td width="10"> </td>
<td>Display users logged in and what they are doing.</td>
</tr>
<tr>
<td>wall</td>
<td width="10"> </td>
<td>Send a message to everybody's terminal.</td>
</tr>
<tr>
<td>who</td>
<td width="10"> </td>
<td>Display the users logged in.</td>
</tr>
<tr>
<td>whoami</td>
<td width="10"> </td>
<td>Print effective user id.</td>
</tr>
</table>


== Updating Packages in Ubuntu Server ==
== Updating Packages in Ubuntu Server ==

Revision as of 13:48, 17 August 2016

Allow port 3306 to be accessible externally

edit the /etc/mysql/my.cnf # the bind address which is usurally 127.0.0.1

Installing Bittorrent Sync

sh -c 'echo "deb http://linux-packages.getsync.com/btsync/deb btsync non-free" > /etc/apt/sources.list.d/btsync.list'
 
wget -qO - http://linux-packages.getsync.com/btsync/key.asc | sudo apt-key add - 
sudo apt-get update
 
sudo apt-get install btsync

Autostart Bitsync: add "Service btsync start" to the /etc/rc.local file 

== How to Use BT sync:==

There’s already a few great tutorials about setting up Btsync in Ubuntu around the web. And below is a brief how-to:

First create a shared folder and set its permissions, here I created a folder shared_folder under the root of my current user:

cd && mkdir shared_folder

sudo chown YOUR_USER:btsync shared_folder

sudo chmod 2775 shared_folder

sudo usermod -a -G btsync YOUR_USER
Then start the btsync service:

sudo service btsync start
You may replace start with stop, enable, disable, or status to control Btsync.

Now go to localhost:8888 in your web browser and add the previous created folder:

Finally share the link, key, or QRcode with your friends and enjoy!

GuruPlug Server

 
Ip is set to DHCP at boot by a script. so even if you edit the /etc/interface file and add Static ip's it will change on reboot. In order to fix this this you need to edit the /etc/ifplugd/ifplugd.action file

and # dhclient3 -e IF_METRIC=100 -pf /var/run/dhclient.eth0.pid -lf /var/lib/dhcp3/dhclient.eth0.leases eth0 

line


Updating Packages in Ubuntu Server

  • Update the Package Index: The APT package index is essentially a database of available packages from the repositories defined in the /etc/apt/sources.list file. To update the local package index with the latest changes made in repositories, type the following:

    sudo apt-get update

     

  • Upgrade Packages: Over time, updated versions of packages currently installed on your computer may become available from the package repositories (for example security updated). To upgrade your system, first update your package index as outlined above, and then type:

    sudo apt-get upgrade

     

    If a package needs to install or remove new dependencies when being upgraded, it will not be upgraded by the upgrade command. For such an upgrade, it is necessary to use the dist-upgrade command.

    Also, you may upgrade your entire Ubuntu system from one revision to another with dist-upgrade. For example, to upgrade from Ubuntu version 5.10 to version 6.06 LTS, you would first ensure the version 6.06 LTS repositories replace the existing 5.10 repositories in your computer's /etc/apt/sources.list, then simply issue the apt-get update command as detailed above, and finally, perform the actual upgrade by typing:

    sudo apt-get dist-upgrade

     

    After a fairly considerable amount of time, your computer will be upgraded to the new revision. Typically, some post-upgrade steps would be required as detailed in the upgrade notes for the revision you are upgrading to.

    Actions of the apt-get command, such as installation and removal of packages, are logged in the /var/log/dpkg.log log file.

  • Remove a Package: Removal of a package or packages is also a straightforward and simple process. To remove the nmap package installed in the previous example, type the following:

    sudo apt-get remove nmap

     

     


    Tip: Multiple Packages: You may specify multiple packages to be installed or removed, separated by spaces.

Black Screen on Linux Boot

1- In linux, if the screen goes black because Xorg didn't start, you can still get to a terminal by using ctrl+alt+F1 or F2 etc. F7 I believe is the Xserver. You can do this even while X is running to get back to a plain text terminal. You can also exit X by using ctrl+alt+backspace if it is still operational.

Installing GUI in Ubuntu Server

 

sudo apt-get install ubuntu-desktop

OR

sudo apt-get install kubuntu-desktop

Startx - to start Gui

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