env command tutorial in linux/unix with examples and use cases

linux env command – run a program in a modified environment

The env command executes another program after modifying the environment as specified on the command line. When the env command is used without parameters, it prints a list of current environment variables.

Syntax

env [OPTION]... [-] [NAME=VALUE]... [COMMAND [ARG]...]

Options

• -i, –ignore-environment
  start with an empty environment
• -0, –null
  end each output line with NUL, not newline
• -u, –unset=NAME
  remove variable from the environment
• -C, –chdir=DIR
  change working directory to DIR
• -S, –split-string=S
  process and split S into separate arguments; used to pass multiple arguments on shebang lines
• -v, –debug
  print verbose information for each processing step

Examples

Print a list of the current environment variables

➜  ~ env

Removes the specified variable from the current environment

➜  ~ env -u MAIL

Use the env command to temporarily change the environment

➜  ~ env SHELL=/bin/bash

Used to pass multiple arguments on shebang lines

Running a script named script.pl containing the following first line:

#!/usr/bin/env -S perl -w -T

Will execute perl -w -T script.pl .