On Fri, Jul 19, 2024 at 20:12:14 +0800, p...@gmx.it wrote:
> for example, what's the difference between '/usr/bin/perl' and 'env
> perl' ?
"env perl" searches your $PATH.
> I know env may set a environment variable in system, so my question also
> includes:
env is used to *display* the current shell environment, or to set a new
environment for *one* specific process.
E.g.
env FOO=bar ./myprogram
This launches ./myprogram with the additional environment variable FOO
set to the value bar.
> 1. where to see a shell environment variable? I tried 'echo $ENV'
> showing nothing.
Just run env with no arguments.
> the key for perl is "_" in environment variable? under this key, why
> 'env perl' just works?
The _ environment variable is weird. Please ignore it for now. You
can live a full and happy life without ever worrying about it.
