env

Show the environment

$ env

$ env [program]

$ env [[-i|--ignore-environment]] [program]

$ env [[-u|--unset]] [variable] [program]

$ env [variable]=[value] [program]

$ env [variable1=value variable2=value variable3=value ...] [program]

$ env [[-a|--argv0]] [custom_name] [program]

env [OPTION]... [-] [NAME=VALUE]... [COMMAND [ARG]...]
Without COMMAND, print the current environment.

-i, --ignore-environment
    Start with an empty environment

-u, --unset=NAME
    Remove specified variable from environment

-C DIR, --chdir=DIR
    Change working directory to DIR before executing command

-S STRING, --split=STRING
    Use STRING as separator for multiple commands

-v, --verbose
    Print verbose information

--help
    Display help and exit

--version
    Output version information and exit

The env command executes a specified program in a customized environment. It allows setting, unsetting, or clearing environment variables before running the command. If no command is provided, env simply prints all current environment variables, one per line, in NAME=VALUE format.

Common uses include temporarily overriding variables for scripts, creating clean environments with -i, or unsetting specific variables. For example, env -i PATH=/bin:/usr/bin command runs command in an empty environment except for PATH.

It supports changing the working directory with -C and verbose output with -v. A lone - or -- implies -i. env is part of GNU coreutils and POSIX-compliant, making it portable across Unix-like systems. It's useful for debugging, testing programs under different conditions, or in scripts requiring isolated environments.