Command Line – Environmental Variables » Linux Magazine

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Environmental variables often operate quietly in the background, but knowing how to set, modify, and delete them can come in handy.

Roughly speaking, environmental variables may be thought of as the configuration files for a user account. Operating behind day-to-day operations, environmental variables define the resources available to an account. While it is perfectly possible to ignore environmental variables when running a Linux account, you may need to edit them sometimes to correct a gap in functionality, especially after new packages are installed. For this reason, it makes sense to know how to set, modify, and delete environmental variables. On networks, you’ll also want to safeguard them against security breaches.

Structurally, environmental variables resemble the fields found in most applications’ configuration files. For instance, Python’s setting.py contains such variables as $ENGINE, $HOST, and $POST. Some of these applications are global, such as the systemd variables contained in /etc/experiment.d, which include the resources that GTK and Qt use to interact with system. Similarly, permanent Bash variables are stored in .bash_profile in an account’s home directory, while Bash variables such as aliases are stored in .bashrc.

In contrast, environmental variables are general settings for a particular account, rather than values for an entire system or a particular application. Confusion arises because all these types of variables are similar in structure. When referred to in the abstract, all these variables use the same structure such as $HOME. The following three formats are used in all these circumstances:

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