If an ENV is defined as a global scope variable, its value is defined for all the programs or scripts run in that terminal.
Define a global env in terminal:
$ export <varname>=<value>
There is no space between name, =, and value. Otherwise, each of the three will be considered as a separate command, thus raising an error.
Now, Just place a $ before the varname and Linux will take care of replacing it with its value.
Type on the command line or use it in any script:
$ echo $<varname>
echo command is just an example, environment variables can be used in the same way with any Linux command.
Global ENVs are global only in the context of a terminal from which it is defined, Hence even being global ENV will not be valid for a terminal other than the genesis terminal of the ENV.
For persisting the ENV, This is what we will explore in Persisting ENVs section.
Local scoped ENVs can only be accessed by the terminal itself and not by any program or shell script even if the latter is started by the same terminal for which the local scoped ENV is defined.
Define a local env in terminal:
$ <varname>=<value>
Accessing local scoped ENV is done the same way you access a global scoped ENV.
| Command | Description |
|---|---|
echo $<varname> |
To display value of a variable |
env |
Displays all environment variables |
<varname>=<value> |
Create a new local variable |
unset <varname> |
Remove a variable |
export <varname>=<value> |
To set value of an environment variable |