Use the following command to modify the .bashrc file:
gedit ~/.bashrc
Modify the end of the file:
source /opt/ros/indigo/setup.bash
source ~/catkin_ws/devel/setup.bash
As for what is an environment variable, for a common example, in Windows system, when we install the JDK, if we directly enter java or javac related commands in the command prompt line (cmd),
it will prompt: "java It is not an internal or external command, nor an executable program or batch file." At this time, we need to add the path of the bin directory in the JDK to the PATH variable.
1 Use /etc/profile
/etc/profile Modifying environment variables is effective for all users, but must source /etc/profile after modification
1) Modify the /etc/profile file
sudo vi /etc/profile
2) Add environment variables at the end of the /etc/profile file
变量名=变量值
...=...
export 变量名 ...
如：JAVA_HOME=/opt/jdk1.8.0_91
CLASSPATH=.:./bin
PATH=$JAVA_HOME/bin:$PATH
export JAVA_HOME CLASSPATH PATH
3) Exit and save
:wq
4) Effective immediately
source /etc/profile
Note: If you do not execute the source command, you need to restart the system to take effect
2 Use .bashrc
.bashrc Modify this file in a user's home directory, which only takes effect for the current user. It is recommended to use this to have the least impact, and it must be sourced after the modification.
2.1 Add environment variables
Assume that the environment variable path you want to add is: /opt/my-tools/android-sdk/tools
- Enter the user's root directory
cd $HOME 或 cd ~
- Then open .bashrc if it does not exist, create a new .bashrc file
vi .bashrc
- Add the path you want to add at the end of the .bashrc page
export PATH=$PATH:/opt/my-tools/android-sdk/tools
- Final execution
source ~/.bashrc
Environment variables are working.