How to execute perl command in current Bash process

Question

Today, I write a bash script to open and close a special python virtual envionment. You want to close the virtual environment, you must in the same bash process with command deactivate, so you can use command ~source~ to execute you bash script.(Preface)

Perl question

Here is my perl script

#!/usr/bin/perl 
BEGIN{
    $\="";
}
use warnings;
use strict;
use feature "switch";
use Cwd qw(chdir cwd);
no warnings "experimental::smartmatch";
our $path = $ENV{"PATH"};

if($path =~ /sspider\/bin/){
    print "Scrapy virtual environment opened already\n";
    print "Do you want to close it? [y/n]:";
    chomp(my $answer = <STDIN>);
    given($answer){
        when(/[yY\n]/){
            my @path = split(/:/, $path);
            my $scrapy_path;
            for (@path){
                if(/sspider/){
                    $scrapy_path = $_;
                }
            };
            print $ENV{PWD}, "\n";
            chdir("$scrapy_path") or die "Can't goto scrapy bin directory";
            print $ENV{PWD}, "\n";
            system("deactivate");
            print "Closed successfully\n";
        }
    }
}

Because when I execute the perl script, it is running in a new process, so it can't close the virtual environment.

So, I want to know how to solve it.(Execute a command in the current bash process in perl script.

Process

Perl

In bash: exec myscript.pl to replace the bash process with it? — Shawn
– Shawn, Commented May 28, 2022 at 13:43
The solution is to stop using virutalenv. The entire approach is fatally flawed and absurd. But....all it really does is set a few environment variables like PYTHONPATH and PATH and VIRTUALENV. Read through the activate script and see what it's doing...it's not much. Set your PYTHONHOME as needed and move one. — William Pursell
– William Pursell, Commented May 28, 2022 at 14:12
@Shawn I can't understand your meaning, when I use exec command, the bash process exit at the moment. — ssayno
– ssayno, Commented May 28, 2022 at 14:31
@WilliamPursell I use the venv moudle, and I write this script just for fun.-:) — ssayno
– ssayno, Commented May 28, 2022 at 14:32

Steffen Ullrich · Accepted Answer · 2022-05-28 14:01:35Z

1

It is impossible to run Perl code as part of the current bash process. Bash cannot execute Perl code by its own so it needs to run the Perl interpreter - which is separate program and thus will run as a new process.

What might be done though is to create some file by the Perl program which then gets sourced by the shell - thus running the shell-instructions in this created file in the context of the current shell.

answered May 28, 2022 at 14:01

Steffen Ullrich

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8 Comments

ssayno Over a year ago

Ok, thanks for your answer. I thought that I can with some command go to the parent process, so funny.-:)

ikegami Over a year ago

Re "I thought that I can with some command go to the parent process", You can find the parent process. But then what? How do you tell an already running bash to execute a command? That's the impossible part.

ssayno Over a year ago

@ikegami I know it's impossible, so I add "so funny" after that.

ikegami Over a year ago

@zhou alias Re "I know it's impossible", I said it's NOT impossible. It's quite easy, in fact, to "go to" the parent process.

ssayno Over a year ago

@ikegami Sorry, these day I can't login this website.Can you tell me how to "go to" the parent process with perl?

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