For the purpose of this guide, we will divide the Linux distributions nowadays available into three big families:

1. APT based Linux distributions (Ubuntu, Mint) - those distributions use the Advanced Packaging Tool to fetch and install software packages in a semi-automatic way, resolving and taking care of dependencies. 
2. RPM based Linux distributions (Suse, OpenSUSE, Red Hat, CentOS, Fedora, Oracle Linux) - those distributions allow the installation of software packages (.rpm files), which contain the binary files to be installed on the system and an integrated dependency checker script. The .rpm packages allow a simplified and smooth installation of software without requiring a deep knowledge of the system.
3. Other Linux distributions  - those distributions may or may not use a specific package manager but all of them allow the installation of software using the source code package (.tar.gz) through a series of command to be issued on the Terminal.

How to install the official Oracle Java on APT based Linux distributions

The most simple way to install Java on Ubuntu or Mint is using the webupd8 repository. This method will install the latest version of JDK 8 and the JRE 8 browser plugin. The supported versions are: Ubuntu 15.04, 14.10, 14.04, 12.04 - Linux Mint 17.1, 17, 13

For details, please refer to: http://www.webupd8.org/2012/09/install-oracle-java-8-in-ubuntu-via-ppa.html

a. On your Linux machine, open the "Terminal". If you need help with accessing and using the Terminal, please refer to: https://help.ubuntu.com/community/UsingTheTerminal

b. Become root, by typing su on the Terminal and entering the super user password. Instead of becoming root, you can choose to use the sudo feature (which gives your user the root privileges for a single command). If you want to use sudo, just add sudo before each one of the commands you will enter in the Terminal. You will be requested to enter the sudo password.

c. Add the webupd8 repository by tiping add-apt-repository ppa:webupd8team/java Follow the instructions on the screen. You should be asked to press [ENTER] to continue. Once done, the repository will be added.

d. Type the command apt-get update

e. Enter the command: apt-get install oracle-java8-installer The process will download and install automatically the required packages along with their dependencies. Once the command has completed, the Oracle Java platform will be ready to be used.

Should you prefer to have control of all the phases of the installation, instead of relying on the APT facility, please refer to the instructions on this page: http://www.wikihow.com/Install-Oracle-Java-JRE-on-Ubuntu-Linux

How to install the official Oracle Java on RPM based Linux distributions

a. On your Linux machine, open the "Terminal". If you need help with accessing and using the Terminal, please refer to: https://help.ubuntu.com/community/UsingTheTerminal

b. Become root, by typing su on the Terminal and entering the super user password. Instead of becoming root, you can choose to use the sudo feature (which gives your user the root privileges for single commands). If you want to use sudo, just add sudo before each one of the commands you will enter in the Terminal. You will be requested to enter the sudo password.

c. Create the folder /usr/java by issuing the command mkdir /usr/java. If the directory already exists you will see a message indicating that. In this case you can proceed directly to point d.

d. Go to the page https://www.java.com/en/download/linux_manual.jsp

e. If you have a 32 bit system, download the file "Linux RPM" . If you have a 64 bit system, download the file "Linux64 RPM". In either case, please instruct your browser to save the file in the folder /usr/java or move the file to that foder once it has been downloaded.

f. Go back to the Terminal and move to the /usr/java folder by typing cd /usr/java

g. List the content of the folder by typing the command ls -la You should see the file you downloaded. It will be called jre-XuYY-linux-ARCH.rpm (where X is the Java family, YY the update number and ARCH will be i586 for 32 bit installer and x64 for 64 bit installer)

h.  Launch this command to perform the installation: rpm -ivh jre-XuYY-linux-ARCH.rpm  Obviously you need to use the real file name, for example jre-8u65-linux-x64.rpm

Once the installation has been performed, the Oracle Java should be ready to be used. Usually a system restart is not required on Linux machines. In case you see warning or error message/s during the installation, please check their content and search the Internet for possible solutions. Most of the time the warning/error messages maight refer to missing dependencies (this means that another package needs to be installed before you can install Java) or to unsufficient privileges (this means that you are launching the command with a regular user instead of "root"). If you cannot find the proper course of actions to overcome the issue, please refer to the support documentation or forums for your current Linux distribution.

How to install the official Oracle Java on other Linux distributions

If your Linux distribution does not support RPM or APT package managers, the installation of Oracle Java can be performed manually in this way:

a. On your Linux machine, open the "Terminal".

b. Become root, by typing su on the Terminal and entering the super user password. Instead of becoming root, you can choose to use the sudo feature (which gives your user the root privileges for single commands). If you want to use sudo, just add sudo before each one of the commands you will enter in the Terminal. You will be then required to enter the sudo password.

c. Create the folder /usr/java by issuing the command mkdir /usr/java. If the directory already exists you will see a message indicating that. In this case you can proceed directly to point d.

d. Go to the page https://www.java.com/en/download/linux_manual.jsp

e. If you have a 32 bit system, download the file "Linux" . If you have a 64 bit system, download the file "Linux x64". In either case, please instruct your browser to save the file in the folder /usr/java or move the file to that foder once it has been downloaded.

f. Go back to the Terminal and move to the /usr/java folder by typing cd /usr/java

g. List the content of the folder by typing the command ls -la You should see the file you downloaded. It will be called jre-XuYY-linux-ARCH.tar.gz (where X is the Java family, YY the update number and ARCH will be i586 for 32 bit installer and x64 for 64 bit installer)

h.  Launch this command to perform the installation: tar zxvf jre-XuYY-linux-ARCH.tar.gz  Obviously you need to use the real file name, for example jre-8u65-linux-x64.tar.gz

i. Once done, enter command ls -la You will see the folder /usr/java/jre1.X.0_YY (where X is the Java family, YY the update number)

l.  The Java executables are now present in the folder /usr/java/jre1.X.0_YY/bin 

m. Now check which is the symbolic link used by the system to access the java executables by entering the commands:

which java  - you will receive an output similar to this: /usr/bin/java  From now on we will refer to this path as javasympath.

which javac  - you will receive an output similar to this: /usr/bin/java  From now on we will refer to this path as javacsympath.

which javaws  - you will receive an output similar to this: /usr/bin/java  From now on we will refer to this path as javawssympath.

Unless your are launching the java applications using the full path (for example /usr/java/jre1.X.0_YY/bin/java ...), you would need to tell your system which java executables should be used when a generic java command is issued. In order to to this, you can either update your alternatives files (if your system supports them) or the symbolic links. Here below you can see the instructions, according to your system:

- If your system uses the alternatives files:

n.  Issue the following commands, paying attention to make the necessary substitutions .

update-alternatives --install javasympath java /usr/java/jre1.X.0_YY/bin/java 1

update-alternatives --install javacsympath javac /usr/java/jre1.X.0_YY/bin/javac 1

update-alternatives --install javawssympath javaws /usr/java/jre1.X.0_YY/bin/javaws 1

- If your system does not use the alternatives files:

n. Issue the following commands, paying attention to make the necessary substitutions .

ln -sf  /usr/java/jre1.X.0_YY/bin/java javasympath

ln -sf /usr/java/jre1.X.0_YY/bin/javac javacsympath

ln -sf /usr/java/jre1.X.0_YY/bin/javaws javawssympath

In order to opt back into the Secure Login System, please proceed as follows:

1. Open your browser and go to the web page ibkr.com.

2. Click on Log In > Portal Login

3. Enter your credentials and complete the authentication using your security device

6. You will see a box titled "Secure Login Settings". Within that box, click on the Configure "gear" icon. This will take you to the settings for Secure Login not required for trading.

7. Select the radio button next to "I want to always use my Secure Login Device when logging in" and click on Continue

8. You will receive a confirmation that your settings have been updated. Click on OK to finalize the procedure

 References

• See KB1131 for an overview of the Secure Login System
• See KB1943 for instructions on requesting a replacement Digital Security Card+
• See KB2636 for information and procedures related to Security Devices
• See KB2481 for instructions about sharing the Security Login Device between two or more users
• See KB975 for instructions on how to return your security device to IBKR
• See KB2260 for instructions on activating the IB Key authentication via IBKR Mobile
• See KB2895 for information about Multiple 2Factor System (M2FS)
• See KB1861 for information about charges or expenses associated with the security devices
• See KB69 for information about Temporary passcode validity

NOTE: If you have already agreed to the API License Agreement please start at Step 3 below.

Instructions

1. Click directly on the button below to access the API software download page
   
2. This will direct you to Interactive Brokers API License Agreement, please review it
3. Once you have clicked "I Agree", refer to the Mac / Unix section to download the API Software version of your preference
   

4. This will download twsapi_macunix.n.m.zip to your computer
   (where n and m are the major and minor version numbers respectively)
5. Open Terminal (Ctrl+Alt+T on most distributions)
   (On Mac press Command+Space to launch Spotlight, then type terminal and press Return)
6. Navigate to the directory where the installer has been downloaded (normally it should be the Download folder within your home folder) and confirm the file is present

    $  cd ~/Downloads
    $  ls

7. Unzip the contents the installer into your home folder with the following command (if prompted, enter your password):
   $  sudo unzip twsapi_macunix.n.m.zip -d $HOME/
   
   
8. To access the sample and source files, navigate to the IBJts directory and confirm the subfolders samples and source are present
   $  cd ~/IBJts
   $  ls
   
   

Legacy Instructions - API Version ≤ 9.71

Note: IB only offers API Version 9.72+. In the event you already have an existing legacy version and need to install it, please refer to the directions below:

1. locate the file twsapi_macunix.n.m.jar on your computer
   (where n and m are the major and minor version numbers respectively.)
2. Open Terminal (Ctrl+Alt+T on most distributions)
   (On Mac press Command+Space to launch Spotlight, then type terminal and press Return)
3. Navigate to the directory where the .jar file has been located (normally it should be the Download folder within your home folder) and confirm it is present
   $  cd ~/Downloads
   $  ls
4. Extract the contents of the .jar file into your home folder
   $  jar xf twsapi_macunix.n.m.jar -d $ HOME/
5. To access the sample and source files, navigate to the IBJts directory and confirm the subfolders samples and source are present
   $  cd ~/IBJts
   $  ls

Please follow the below steps to transfer your TWS layout settings from one user to another:

1. Log in to TWS with the user whose settings you would like to export

2. Navigate to the top menu File followed by Layout Settings > Save Decrypted Settings As...

3. Click Yes on the warning pop up

4. Open the Look In drop-down and select the folder (e.g. Desktop) where you want the decrypted settings file to be saved

5. Choose a name of your preference (e.g., migrate) and click Save. A pop-up will flash to inform you that the file has been written

6. Restart the TWS. Log in with the user which should import the layout settings

7. In the top left, click on File > Layout Settings > Layout/Settings Recovery

8. Select Custom and click OK

9. Open the Look In drop-down and select the location where you previously saved the decrypted settings file (step 5). Click Open

10. Click Open without reporting problem

11. Your TWS will automatically restart, loading the imported layout settings

References

See KB2323 for instructions on how to restore TWS settings from external storage

See KB2282 for instructions on how to transfer settings from one computer to another.

See KB3146 for instructions on how to overcome the "Download settings from server failed" error