my $var = "foobarfoobaz";
$var =~ s/foo//;
say $var;   # says "barfoobaz"

##</code><code>##

my $var = "foobarfoobaz";
$var =~ s/foo//g;
say $var;   # says "barbaz"

##</code><code>##

my $var = "foobarfoobaz";
$var =~ s@foo@@g;
say $var;   # says "barbaz"

##</code><code>##

my $var = "foobarfoobaz";
$var =~ s{foo}{}g;
say $var;   # says "barbaz"