Setting global environment variables in linux

Setting environment variable globally without restarting Ubuntu

But that requires system restart or X restart. Is it possible to set an environment variable in Ubuntu / Linux so that immediately available system wide without restarting OS or logging out the user?

This means you cannot do what you ask, then: you will at least have to restart X. You cannot change the environment of an already running process.

@fge actually, you can but it requires you to attach to the process with gdb . It works but it’s very hackish

3 Answers 3

The simple answer is: you cannot do this in general.

Why can there be no general solution?

The «why?» needs a more detailed explanation. In Linux, the environment is process-specific. Each process environment is stored in a special memory area allocated exclusively for this process.

As an aside: To quickly inspect the environment of a process, have a look at /proc//env (or try /proc/self/env for the environment of the currently running process, such as your shell).

When a («parent») process starts another («child») process (via fork(2) ), the environment the environment of the parent is copied to produce the environment of the child. There is no inheritance-style association between those two environments thereafter, they are completely separate. So there is no «global» or «master» environment we could change, to achieve what you want.

Why not simply change the per-process environment of all running processes? The memory area for the environment is in a well-defined location (basically right before the memory allocated for the stack), so you can’t easily extend it, without corrupting other critical memory areas of the process.

Possible half-solutions for special cases

That said, one can imagine several special cases where you could indeed achieve what you want.

• Most obviously, if you do «size-neutral» changes, you could conceivable patch up all environments of all processes. For example, replace every USER=foo environment variable (if present), with USER=bar . A rather special case, I fear.
• If you don’t really need to change the environments of all processes, but only of a class of well-known ones, more creative approaches might be possible. Vorsprung’s answer is an impressive demonstration of doing exactly this with only Bash processes.

There are probably many other special cases, where there is a possible solution. But as explained above: no solution for the general case.

Источник

How to Change Environment Variables in Bash on Linux: A Comprehensive Guide

Learn how to change environment variables in Bash on Linux with this comprehensive guide. Discover best practices, tips, and tricks for setting up global environment variables.

• Using the export command to set environment variables
• Setting permanent environment variables for a single user
• How To Use Shell Environment Variables
• Setting up global environment variables
• Defining shell variables with and without ‘export’
• Best practices, tips, and tricks for setting environment variables
• Other helpful code examples for changing environment variables in Bash on Linux
• Conclusion
• How do I change environment variables in Linux?
• How do I change a .env variable?
• How do I change environment variables in shell?
• How do I pass an environment variable in Bash script?

Bash is a popular shell used in Linux systems, and one of the most common tasks performed in this environment is changing environment variables. setting environment variables is essential for enabling programs to access important information and allowing for greater customization and control. In this blog post, we will discuss how to change environment variables in bash on Linux, covering key points, important points, and helpful points to help you get started.

Using the export command to set environment variables

The export command is a built-in shell command for Bash that is used to export an environment variable to allow new child processes to inherit it. To set an environment variable every time, use the export command in the .bashrc file (or the appropriate initialization file for your shell). Always surround variables usage with quotes to prevent word splitting and globbing.

Here is an example of how to set the MY_VAR environment variable using the export command in Bash:

Now, the MY_VAR environment variable has been set to “Hello World”. To verify that the environment variable has been set, use the echo command to print the value of the variable:

Setting permanent environment variables for a single user

To set permanent environment variables for a single user, edit the .bashrc file. The ~/.bashrc file is used to set permanent environment variables for a single user. The existing environment variables can be listed using export [-p] .

Here is an example of how to set the MY_VAR environment variable permanently for a single user in Bash:

1. Save and close the file.
2. To apply the changes, either log out and log back in or run the following command:

Now, the MY_VAR environment variable has been set permanently for a single user.

How To Use Shell Environment Variables

In this video, I am going to give a cursory introduction to shell environment variables, which come Duration: 15:08

Setting up global environment variables

To set up global environment variables, use the export command. best practices for setting environment variables include setting them up globally, using the export command, and surrounding variables usage with quotes. The $PATH variable is a popular environment variable to edit, as it lets you specify the directories Bash should search for programs when you run them.

Here is an example of how to set the MY_VAR environment variable globally in Bash:

1. Save and close the file.
2. To apply the changes, either log out and log back in or run the following command:

Now, the MY_VAR environment variable has been set globally.

Defining shell variables with and without ‘export’

There are two different ways of defining a shell variable: with and without the use of ‘export’. Environment variables set through these commands are available only for the current session. Bash scripts can also be passed with the arguments in the form of environment variables.

Here is an example of how to define a shell variable with and without the use of ‘export’ in Bash:

MY_VAR="Hello World" # Without 'export' export MY_VAR="Hello World" # With 'export' 

Best practices, tips, and tricks for setting environment variables

Best practices for setting global environment variables include using the export command and surrounding variables usage with quotes. Tips for Setting environment variables include using descriptive names, avoiding spaces in variable names, and using uppercase letters for constants. Tricks for setting environment variables include using aliases to shorten long variable names and using variable substitution to simplify complex commands.

Here are some best practices, tips, and tricks for setting environment variables in bash:

• Always use the export command to set environment variables.
• Surround variables usage with quotes to prevent word splitting and globbing.
• Use descriptive names for environment variables.
• Avoid spaces in variable names.
• Use uppercase letters for constants.
• Use aliases to shorten long variable names.
• Use variable substitution to simplify complex commands.

Other helpful code examples for changing environment variables in Bash on Linux

In shell, how to set environment variable using bash code example

# set variable environment export fullname="restu wahyu saputra" echo $fullname

# Linux - Bash# syntax # export *=*;# example export ORACLE_SID='sales_database';

In shell, setting environment variables bash code example

export VARNAME="my value" # shorter, less portable version 

Conclusion

Setting environment variables is a common task in Linux systems, and understanding how to do it properly can help you customize your environment and achieve greater control over your programs. We hope that this blog post has been helpful in explaining how to change environment variables in Bash on Linux, covering key points, important points, and helpful points to guide you through the process. Remember to always use best practices, tips, and tricks when setting environment variables to ensure that your system is secure and efficient.

Источник