[Linux] Bash env uso equivalente: Manage environment variables

Overview

The env command in Bash is used to run a command in a modified environment. It allows you to set or unset environment variables for the command you want to execute, making it a useful tool for testing and running applications with specific configurations.

Usage

The basic syntax of the env command is as follows:

env [options] [arguments]

Common Options

• -i: Start with an empty environment, ignoring the current environment variables.
• -u NAME: Remove the variable NAME from the environment.
• -0: Use a null character as the delimiter instead of a newline (useful for handling filenames with spaces).

Common Examples

1. Running a command with a modified environment variable:

   env VAR=value command
   

   This sets VAR to value only for the execution of command.

2. Clearing all environment variables:

   env -i bash
   

   This starts a new Bash shell with no inherited environment variables.

3. Removing a specific environment variable:

   env -u VAR command
   

   This runs command without the environment variable VAR.

4. Listing all current environment variables:

   env
   

   This displays all the environment variables currently set in the shell.

5. Running a script with a specific environment:

   env PATH=/custom/path ./script.sh
   

   This executes script.sh with a modified PATH.

Tips

• Use env to test scripts in a clean environment to avoid unexpected behavior due to inherited variables.
• When scripting, consider using env to ensure that your scripts run with the correct interpreter by specifying it at the top of the script (e.g., #!/usr/bin/env python).
• Be cautious when using -i, as it will remove all environment variables, which might affect the execution of commands that rely on them.