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What is the env command?
The env command is a popular command-line utility in Unix-like operating systems that allows users to manipulate and view the environment variables within their current shell session. Environment variables are a fundamental part of the operating system, storing information such as system paths, configuration settings, and user-specific preferences.
How to use commands that manipulate environment variables
There are several commands available for manipulating environment variables in different ways. This blog post will cover some of the commonly used ones.
1. env
The env command, as mentioned earlier, is primarily used to view and modify environment variables. By running the env command without any arguments, you can display a list of current environment variables. For example:
“`
$ env
“`
This will output a list of variables in the format `VAR_NAME=VALUE`.
To modify an environment variable, you can use the syntax `VAR_NAME=NEW_VALUE` followed by the command you want to run. For instance:
“`
$ DEBUG=true env node app.js
“`
In the above example, the `DEBUG` environment variable is set to `true`, and then the `node app.js` command is executed.
2. export
The export command is used to define new environment variables or modify existing ones in the current shell session. To create a new environment variable, use the syntax `export VAR_NAME=VALUE`. For example:
“`
$ export MY_VAR=my_value
“`
This will set the environment variable `MY_VAR` to the value `my_value`.
To check if the variable has been successfully set, you can use the env command mentioned earlier:
“`
$ env | grep MY_VAR
“`
This will display the value of `MY_VAR` if it has been set.
3. unset
The unset command allows you to remove environment variables from the current shell session. To remove a variable, simply run:
“`
$ unset VAR_NAME
“`
Replace `VAR_NAME` with the name of the environment variable you wish to remove.
Conclusion
In this blog post, we have explored the env command and some other commonly used commands for manipulating environment variables. Understanding and effectively using these commands can greatly enhance your workflow and allow you to customize your shell environment according to your needs. Experiment with these commands, and unlock the power of environment variables in your Unix-like operating system.
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