Combine redirecting open() to scalar with system() - perl

Question

I wrote a routine to "safely" execute some command, and I wanted to capture STDOUT and STDERR in string variables using open(STDOUT, '+<', \$stdout) and similar for STDERR.
I verified via print "Test\n" and print STDERR "Test2\n" that the redirection works inside the routine (I can find the outputs in $stdout and $stderr).
However when I run the command through system() (Perl's version), the output still goes to the terminal.
So I wonder: Is opening a scalar value available for Perl's own I/O only?
And if so, how would I capture the STDOUT and STDERR from the system() call without using temporary files (having their own issues)?
(I've seen https://stackoverflow.com/a/109672/6607497 already)
The preferred solution (if such exists) should use as few extra packages as possible, and it should run with SLES 12 or SLES 15 (openSUSE Leap 15.2).
Those distributions only offer a limited set of Perl modules.

Answer 1

You can easily do this using IPC::Run to capture output.
Test script that writes to standard output and error:
#!/bin/sh
# demo.sh
echo "To Standard Output"
echo "To Standard Error" >&2
and perl script that runs it:
#!/usr/bin/env perl
use warnings;
use strict;
use IPC::Run qw/run/;
my ($out, $err);
run ["sh", "demo.sh"], \undef, \$out, \$err;
print "Standard output: ", $out;
print "Standard error: ", $err;
gives the following output:
$ perl demo.pl
Standard output: To Standard Output
Standard error: To Standard Error
Alternative using IPC::Run3 (Which might be more desirable if you don't need any of IPC::Run's more advanced features):
#!/usr/bin/env perl
use warnings;
use strict;
use IPC::Run3;
my ($out, $err);
run3 ["sh", "demo.sh"], \undef, \$out, \$err;
print "Standard output: ", $out;
print "Standard error: ", $err;