If there is no assignment of environment variable following `env`, what kind of environment is a command executed with?

Question

env runs a command with a modified environment.

env [option]... [name=value]... [command [args]...]

If there is no name=value or option following env, what kind of environment is a command executed with?

What is the purpose of using env without any name=value or option following?

env bash -c 'echo "$_"'

Thanks.

Do you mean see `bash: set: No such file or directory` after running `env bash -f 'set'`? — Tim, Aug 02 '17 at 16:03
`set` display all the shell variables and functions. What is it to do with environment variables? — Tim, Aug 02 '17 at 16:26

Ulrich Schwarz · Answer 1 · 2017-08-02T16:08:02.847

1

The output of

env cat /proc/self/environ

suggests that the environment is unchanged if nothing else is given.

(Or indeed, if I had bothered to read the fine manual, 'If no COMMAND, print the resulting environment', so plain env will be just fine.)

edited Aug 02 '17 at 16:08

answered Aug 02 '17 at 16:05

Ulrich Schwarz

Thanks. Then what is the difference between using `env` and not using `env`? What is the purpose of using `env` without any assignment following? – Tim Aug 02 '17 at 16:06
"no COMMAND" is indeed a totally different situation from no `name=value` and option – Tim Aug 02 '17 at 16:09
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@Tim: you might find https://unix.stackexchange.com/a/29620/3929 helpful. In a nutshell, it can make sure you call a binary, not an alias or function, without knowing where exactly it is (other than in `$PATH`). – Ulrich Schwarz Aug 02 '17 at 16:11

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