Exporting with Environmental Variables: A Beginner’s Guide to Using the Linux Command Line
In the world of Linux, it’s important to know how to use the command line interface (CLI). This is where the real power of Linux lies, and it’s what separates it from other operating systems.
Within the realm of CLI, there are several tools and commands available to achieve a myriad of tasks. In this article, we’ll discuss one such command:
export.
Specifically, we’ll discuss how it’s used with environmental variables. Prerequisite: Setting Up Your Linux Environment
Before we dive into the specifics of
exporting with the
export command, let’s first make sure you’re set up with a Linux environment.
For this guide, we’ll be using a virtual machine (VM) with Ubuntu installed. There are a few steps you’ll need to take:
1.
Install a virtual machine software of your choice
2. Download the Ubuntu installation image and configure it within your virtual machine software
3.
Install Ubuntu within the VM
4. Configure a user account and login
Once you have done these steps, you’ll be ready to start using the Ubuntu CLI.
Export: What Is It and What Does It Do? In the simplest terms, “
export” is a built-in bash shell command that sets the value of the environment variable.
This makes it a powerful tool for working with the Linux command line. Let’s break down what each component of “Export” means:
– “Export” is the command you’ll use when you want to set an environment variable.
– “Shell”: A shell, or command-line interface (CLI), interprets what you type and passes it to the operating system. In our case, we’re using the shell called “Bash,” which is the default shell for most Linux distributions.
– “Environmental Variables”: An environmental variable is a variable that defines the system environment in which different processes run. Here’s a classic example of
exporting with the
export command.
Let’s say you wanted to set an environmental variable called “EDITOR” with the value “nano”. You would achieve that by typing:
“`
export EDITOR=nano
“`
Let’s break this down:
– “
export” is the command you’ll use when you want to set an environment variable. – “EDITOR” is the variable’s name, which is always written in uppercase.
– “nano” is the value assigned to the variable.”nano” is a simple Linux text editor and now the default text editor. We can verify that the variable exists by typing:
“`
echo $EDITOR
“`
This should output “nano” in the terminal.
Exporting with Environmental Variables: Why Is It Useful? By setting environment variables, you can customize the behavior of command-line tools and the system itself.
One classic example of this is the path environment variable, which defines where the system looks for executables. Set this path environment variable and you can specify where the command console should look for executables that you want to run from the command line interface.
So why is “
export” important in the realm of environmental variables? Let’s go with an example to illustrate:
Suppose you’re working on a school Project and making frequent configurations to your VM.
Now, every time you need to make a change, you have to navigate through the file system to find your project’s folder. This becomes really tedious over time.
Thankfully, you can make your life easier by setting an environmental variable that points directly to your project’s folder. In this case, we’ll call the variable “PROJECT_DIR,” but we can name it anything we like.
Set the value, test to be sure you can navigate using the new environment variable easily, and now with a single command, you can navigate directly to the project’s folder anytime you’re working on the project. Here’s how to do this:
“`
export PROJECT_DIR=/path/to/my/project/directory
“`
This makes it super easy to navigate to the project’s folder using the “cd” command:
“`
cd $PROJECT_DIR
“`
Once you’ve set this up, you can put it in a start-up file so it’s always available when you log in. Exporting with Environmental Variables: Advanced Tips and Tricks
Now that you understand
export commands and you know why they are useful, try these advanced tips and tricks for even more environmental variable magic:
1.
Concatenate: You can also concatenate two different environment variables to create a single path. Here’s an example of concatenating the project’s folder path and the executable package path you intend to run so it’s easier to run that package from the command line interface:
“`
export PATH=${PROJECT_DIR}/my/package/bin:$PATH
“`
2. POSIX Compliant: If you’re using the
export command, it’s essential to ensure that your use is POSIX-compliant.
POSIX stands for Portable Operating System Interface and is a standard for Unix/Linux-based devices. It specifies a standard command-line interface may be used across all compatible platforms.
This will help you write scripts that are compatible with as many Linux/Unix distributions as possible.
Conclusion
Exporting with environmental variables is a powerful tool for working with the Linux command line. With just one simple command, you can configure and customize your system as you please.
Whether you’re working on a school project or running a professional Linux system, mastering this skill is a must. Syntax: Mastering the Export Command in Linux
Exporting with environmental variables is one of the most powerful tools in the Linux command-line interface.
In this article, we will go in-depth about the syntax and working of the
export command.
Export Command Syntax and No Arguments
The
export command, without any arguments, displays all of the variables that are currently defined, along with their assigned values. This command shows the environment variables that are available to all shells inheriting from the parent shell:
“`
export
“`
This command lists all of the variables defined in the current environment, including those inherited from the parent shell.
Export Command Working in Linux
The
export command is used to set shell variables in the system’s environment. This is often used to set a path to software, packages, or repositories that are installed on your system.
This can be done for a global environment or session-level for the current process or a child shell. The value that is
exported when using the
export command creates an environment variable that any application or process can access, provided that they have permission to access this information.
The syntax for this is:
“`
export VAR=VALUE
“`
Here, VAR is the name of the environment variable that you want to define and VALUE is the value that you want to assign to the environment variable.
Export Command Options and Features
The
export command comes with various options that you can use to make your work even more efficient. -p Option: Enlisting Names in the Current Shell
The -p option, (short for print), enlists the names of all of the currently defined or
exported shell variables that are available for the current shell:
“`
export -p
“`
The output of the above command lists all of the variables’ names that are currently
exported or defined in the current shell. -f Option: Exporting Bash Functions
The -f option in the
export command is used to
export a function to any child shells.
This option is useful for making unique bash functions available to any child scripts, which can then execute the function locally. To
export a function with a unique function name, you can use the following syntax:
“`
export -f function_name
“`
Here, function_name is the unique name assigned to the bash function. -n Option: Removing Variables
The -n option in the
export command is used to remove environment variables:
“`
export -n VAR
“`
Here, VAR is the variable you want to remove.
Value Assigning Before Exporting a Function
You must assign a value to a variable before you
export a function to the environment. If you are unsure whether a variable has been assigned or not, you can use the printenv command to check the status of the variable:
“`
printenv VAR
“`
Here, VAR is the name of the variable that you want to check.
Name Value Exporting
The
export command can be used to set name-value pairs within the environment. A typical example of name-value pairs can be setting the JAVA_HOME environment variable.
This can be set using the following command:
“`
export JAVA_HOME=/path/to/java
“`
Here, JAVA_HOME is the name of the variable being defined, and the path (or value of the variable) is set using “=/path/to/java”.
Scope Level and Login Shell Verification
Once you have set your environment variables with the
export command as described above, you can then view, modify or remove them. Note that the scope of the environment variables can be either global (defined for all users) or specific (defined for session and local terminals only).
You can check the scope of your environment variables using the following command:
“`
echo $VAR
“`
Here, VAR is the name of the variable whose scope you want to determine. If you are working on a login shell, your environment variables will be defined in /etc/profile, /etc/profile.d, or .bash_profile.
The login shell is the shell that is executed immediately after a user logs in.
Conclusion
The
export command is a powerful tool in the Linux environment, used to set environment variables for path, software, function, value assigning, and name-value pairs. Understanding the syntax and working of the
export command is essential to work with the Linux command-line interface effectively.
The various options and features of the
export command can help you customize your environment variables to your specific requirements. Exporting with environmental variables is a powerful tool for working with the Linux command line, used to set shell variables in the system’s environment for path, software, function, value assigning, and name-value pairs.
In this article, we have covered the syntax and working of the
export command, its options and features, and the scope of environment variables in Linux. Understanding the
export command is essential for anyone working in the Linux environment.
Takeaways from this article include the ability to customize and configure your Linux system environment variables to your specific requirements. The
export command is a versatile tool, and mastering its use is essential for anyone working in the Linux command line.