Hi, use Path::Tiny and edit_lines().

use strict;
use warnings;
use feature 'say';
use Path::Tiny;

my $file = path('file.txt');

$file->spew("foo bar\nfoo bar");

$file->edit_lines(sub{s/bar/baz/});

say $file->slurp;
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Output:

foo baz
foo baz
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Hope this helps!