term_attr: add undercurl

term_attr

@@ -22,6 +22,7 @@ my $attr = {
   italic        => 3,
   bolditalic    => '1;3',
   underline     => 4,
+  undercurl     => '4:2',
   blink         => 5,
   blink_ms      => 6,
   reverse       => 7,
@@ -44,6 +45,11 @@ for my $t( sort { $attr->{$a} cmp $attr->{$b} } keys(%{ $attr })) {
   if($t eq 'underline') {
     printf("\e[$attr->{$t}m$t\e[m\n%s\n", 'https://nounderlineonlinks.se');
   }
+  elsif($t eq 'undercurl') {
+    # https://gitlab.com/gnachman/iterm2/-/issues/6382
+    printf("\e[4:3mundercurl\e[m\n");
+    printf("\e[4;58:5:197;4:3mundercurl, colored\e[m\n");
+  }
   else {
     printf("\e[$attr->{$t}m$t\e[m\n");
   }