use autodie;
use Path::Tiny;

# read the file
my $tpl= path("/home/vincent/.config/kmonad/$config")->slurp;

# perform envsubst
$tpl =~ s/\$ (?| (\w+) | \{(\w+)\} )/$ENV{$1}/gx;

# open a pipe to a child process "kmonad" telling it to read from STDIN
open(my $fh, "|-", "kmonad", "/dev/fd/0");

# Write the template to kmonad's stdin
$fh->print($tpl);
$fh->close;