Env
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External
Internal
Overview
Run a command with a modified environment, or just print the environment if no argument is provided.
/usr/bin/env [utility]
/usr/bin/env bash
Options
-u
If the environment variable whose name follows -u
is in the environment, remove it before processing the remaining options. The value for name must not include the ‘=’ character.
-i
Execute the command with only those environment variables specified by name=value
options. The environment inherited by env
is ignored completely.
No Argument Use
Displays environment values.
Modify the Environment to Run a Command
env SOME_VAR='some value' printenv
will display, among other environment variables, SOME_VAR.
Use env to Dynamically Modify PATH
python --version # returns one version
env PATH=/tmp/some-venv:${PATH} python --version # returns a different version
Use on the Shebang Line
The env
command works by instructing the system to look for the specified interpreter through the PATH
variable and use the first occurrence found.